Using raspi-config to change the audio output will not write to /boot/config.txt, but will change the ALSA (sound system) settings. Changing the settings from the raspi-config will invoke amixer cset numid=3 2 underneath. Try running this command from the command line (exit EmulationStation via the menu or by pressing F4) and see if the settings are kept after a reboot. If that doesn't work, then add more info about your system, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first.

you're right. I was looking in the wrong partition. thank you very much

@fuzzybat23 berryboot works differently. You can mount the partition with the globally shared config.txt though - https://raspberrypi.stackexchange.com/questions/6972/location-of-berryboots-config-txt

Instead of using the "enable_uart=1" line in config.txt, I found out it might be more optimal to activate the voltage on pin 8 from inside the retropie>raspi-config>interfacing options>Serial.

@jonnykesh That sad... But thanks!

@ldonohue85 sweet jelly that's a big one wish I had a big one. yeah you ok with previous advice I thought for a sec you was going crt 15hz. But yeah all good

@dankcushions I see... Thanks.

Thanks for the reply. I did notice something else. Before I flash the image file to the SD card, the format of the SD card is in fact FAT32. After the image is written, it is FAT (not 32). Could this be an issue?

@jabbafeet I don't expect other people's numbers to be useful for other cases, as different TV sets have different requirements. I'd encourage you to follow the steps mentioned in the previous posts and understand what ranges work for you in the end. In one monitor I have I don't need these, in another one I end up needing negative values for some reason.

@ohmycommodore It hasn't stopped it, but I think it's less noticeable.

Thanks a lot! I assumed that because it requires root access, it would be impossible to edit like that. Problem solved! :)