Hi PVC, thanks for the response. The hearing aids are Bernafon Alfa 1 miniBTE T with updated Firmware 1.4.5
Adding the audiogram here is something new to me but will follow up on as there's a lot to learn. Everything here is very new and the different software for the 3 different makes of hearing aids I have acquired over 15 years comes across a little intimidating so with great care I crawl forward in that maze of settings in the Oasis NXT software.
After writing my experiences of 50Hz buzzing, just before calling it quits for the day, I went back in and realized using a touchpad instead of a mouse I may have touched that twice and boosted it way too high. Having saved the original audiogram I reverted back to that. The left ear has profound hearing loss which was evident when I switched the hearing aids from left to right. What I thought was a poor setting on the left hearing aid demonstrated itself by still not hearing better switching the hearing aids around..
Reverting back to the original settings, I did only boost the volume one click upwards for the left side, the 50Hz buzzing is gone now.
I'll see where the saved audiogram resides on this laptop as where it is stored is still a bit of a mystery

. To be continued, and thank you for being there. Kind regards, HansKnowsNuffin'
P.S. it's a pleasure being part of this community. As time goes on, I'll consider changing my name to "HansKnowsSumink" from what I've learned here.