Interesting … I others (including me) have had good sound from Jabra, so perhaps another great example of HAs all sound different to each user. But, this certainly sounds like an adjustment challenge which Costco should be able to resolve. Having said all of this, I used Jabra for 2 mos last fall, I liked the open feel to sound but eventually returned them and went back to using my KS9s.
Do you happen to live in an area with access to more than one Costco location? You could try a different HA center with different staff and see if they can determine anything new/different for you? I have been to Costco locations in other states while traveling, and they all have easy access to your records.
Many others have had good experience with Phillips from Costco. If you’re still in your 6mo trial period, then you could return Jabra and next try Phillips - see if this makes a positive difference for you.