Of course I’m not a Phonak owner so I don’t know how Phonak is set up, but it makes sense that Phonak allows users to set their clicks between 1, 2 or 3 dB
Just for reference for Oticon users who are curious, Oticon similarly gives you 2 options, either 1 or 2.5 dB per click. You can also set the volume range as well. Below are a couple of screenshots for Oticon Genie 2 where you can set those parameters (see bottom part). One thing to mention is that the default volume level may not be in the middle. It may be more toward the right (like the 2.5 dB example below) if your hearing loss is heavy enough that you need a louder amplification. Therefore, you may not have enough reserve gain to go up from default as much as you can go down to 0 dB from default.
But back to @DeafAntifa 's excellent original point to the OP, if you’re new to hearing aids, don’t be afraid to use the volume buttons to adjust to hear more if not enough, or to hear less if too loud, until your next visit where you can get your HCP to fine tune the default level further to be just right for you. The details of how many dBs to increase or decrease are not as important as remembering to make the volume control your friend. I’m an experienced user, but to this day, I still fiddle with my volume control and turn it down so I don’t get overwhelmed in loud places, or turn it up so I can hear better.