This is a normal behavior of the MyPhonak app
Phonak done this by design, to save battery in the HA.
the phone screen goes off → the app disconnects from HA
If you switch phone on again → the app reconnects to the HA ( takes a moment )
What me puzzles is that even the audiologist and Phonak representants are not aware of this.
I’ve found people who works for Phonak seem unaware of what should be happening when ringing the support line with the audiologist.
My NHS Audiologist rang Phonak for support and they told them something completely wrong and in the end, the audiologist realised I was right and Phonak were very wrong.
That’s the problem it disconnects from the program. If I reconnect it I have to reset the program again. This just keeps happening every three minutes or so when the screen goes off. When I turn the phone back on it says not connected and I have to reconnect. The only time it stays on for awhile is if I use it with the tv connector + mic setting but even that will disconnect after about 15 min.
I have tried it with my old iPhone 8 and the audiologist said maybe it was my phone. I bought a new iPhone 13 mini and it does the same thing.
You are saving the program aren’t you?
If yes then 
This was a common issue with Marvel and the App was improved for it to not happen but only from Paradise onwards.
I shall test this. I have Paradise in MyPhonak in my new S23+, and Marvel in my older S21.
Just put a sound source near me (a fan), and ran MyPhonak on:
Marvel M70 & Samsung S21
Paradise P90 & Samsung S23+
I then selected “restaurant” moved the volume sliders right to the top, and noise reduction left to low. This made everything noisy, so I could norice the difference (I didn’t mind this as it took my mind off my Tinnitus).
On both phones, the display stayed active for around 10 minutes, dimmed briefly then off. After about another 4 minutes, the sound dropped to what I guess was the default restaurant program. On waking the screens a “Connection Lost” window was there. I reconnected both. This is what happened next.
Marvel M70
On reconnection, the aids were still in the restaurant setting, but the sliders were in their original position. The only button at the bottom is “Save as new”.
Paradise P90
On reconnection, the aids were still in the restaurant setting, but again the sliders were in their original position. The are however 2 buttons at the bottom, “Update” and “Save as New”. I then changed the sliders as above, pressed “Update”, then let the screen time out. After 15 minutes, I opened the display, and the Connection Lost window was there. The updated sliders were still there, so I suppose this is usable.
I suppose a Save as new in the Marvels could have a similar effect??
There’s no “Update” button, on the Automatic or other Target programs.
Theres lots of talk on this forum that the create a custom program on the App for Marvel doesn’t save once screen turns off.
Phonak did an update to the App but only changed it so the customs programs can be saved with Paradise onwards. It still doesn’t work with Marvel.
Update for custom programs for Paradise only.
Like you, I rarely use the app. Another reason to get your original programs maximised at fitting
Oh yes, I agree.
My programs are perfect as they’ll ever be and I’m happy.
So do you mean every few minutes I have to switch the phone back on and wait for it to reconnect to keep the app working? The sound completely loses the setting I put in every time the the app disconnects and has to be set again. This is just ridiculous. I am so glad I paid all this money for this junk. Even the manufacturer doesn’t seem to know how they work and they don’t seem to be doing anything about it. Thank you everyone that has been trying to help me. I’m just very frustrated that manufacturer and audiologist have no idea how this works and my audiologist is associated with a teaching school. She doesn’t know how the HA work but is teaching new audiology students. Sorry for my rant. Thanks again.
@jacquef2
i think that the app function is intended and also rely on the iOS power saving function and the iOS settings.
Phonak uses Bluetooth Classic , and the BT classic is a power hog , so it can also be that Phonak designed the MyPhonak app this way , if the smarphone going into idle mode , the app closes the BT connection for saving battery of the hearing aids.
I have Phonak Naida M90 and a Xiaomi Mi9 (2019) android phone with latest MyPhonak app version 6.4.1.
Just tried the following, similar like @PeterH did before
Create an individual programm with preferred settings
Opened MyPhonac , selected Restaurant , and tap on “Adjust Program”
By tapping Adjust program you can modify the selected program and then save this as a new programm.
For individual settings
Then tap save as new ← This step is crucial and important !
When you save a individual programm you have to give a name for it.
So i typed “Restaurant Comfort” as name of the altered programm.
This is an individual programm , based on the restaurant programm.
Individual programms getting an star symbol , and the individual programms will be attached on top bar at the end of the row.
Then i waited about 15 minutes , the phone screen went off after 2 minutes (as it is setup in my phone settings) remark: The bluetooth connection is not dropping at the same time the display going of - BT droppes at a later time…
On waking up the phone the MyPhonak app reconnected to the hearing aids. On my phone it take about 3 seconds for reconneting
After reconnection were established, the aids were still in my new individual programm “Restaurant Comfort” that i created before and all settings i made were still there.
Nothing changed back !
So for me it is working flawless. The MyPhonak app need just a short reconnection of 3 seconds
Here is a link to My Phonak App 6.0 User Guide
I didn’t do this step earlier, so good to know that Marvels can hold a program. The downside for all (Marvel, Paradise, Lumity) is that if another program interupts it, it will return to Automatic
since i have no iPhone to try this with myPhonak app, i did a search here in the forum and came across this tread
This tread were a discussion after the release of MyPhonak app version 6.
Ouote: " if you have the ’sounds and haptics’ switched on in your settings (that is what makes the sounds in your phone such as keyboard clicks, this setting is also responsible for the ‘lock sound’ you hear when you turn your phone off) they have found that when an iPhone makes the ‘lock; sound, it puts the iPhone into streaming mode and it reverts back to Autosense - so if this is happening they suggest turning off ’sounds and haptics’ in your settings. This way you can ensure that your hearing aids ’stick’ in the programme you have chosen. "
I don’t know if this issues are still relevant for iPhone , but here this were mentioned
Thank you but I am not sure you are understanding. I am doing exactly as you said . I adjust the program name it, save it and it will work fine until my screen shuts off. Then I hear it change back to autosense. When I open the screen it says not connected. I then have to reconnect and go back to the new program that is set up. This happens every time.
Don’t know if it would help you?
I just looked and it downloaded two days ago. I will have to see if it does anything. Thanks
This happened to me several weeks ago. So frustrating . Then I remembered I had recently downloaded the latest iOS to my phone. So I deleted the Phonic app from my phone, then re-downloaded from the Apple store. And it has worked since.