KS-9 and T-coil Calls

I am upgrading my 6 year old Brio-1 aids with new Costco KS-9 aids and have a question about T-coil on the KS-9. T-coil phone calls with my Samsung S10 phone using my old Brio-1 aids on the T-coil program was great; clear and very crisp. On the new KS-9 aids with the build-in “Phone via T-coil + mic” program T-coil calls using my Samsung S-10 is not as good; not as clear and sort of “muddy” sounding. This T-coil program only has a Balance slider for Surrounding verses Mic setting which seems to have the default balanced for Mic on the myPhonak app. On the old Brio-1 there was no way for me to make any T-coil changes anyway. Can the Costco tech at my next appt make any changes to the T-coil built-in app that would improve the sound quality for these cellphone calls? Thanks.