@mitu , I have a system set up with 4 controllers on my pi400 and would like to use the keyboard to search for the game that I would like to play, from the ALL GAMES list. Is there a way to do this ? I do not want to use the keyboard as a controller, only as a way to input for game selection. Thank you!!

Which emulator are you using ?

Then set the resolution via raspi-config or directly into config.txt, this will set the resolution globally, without the need to run tvservice. See https://www.raspberrypi.org/documentation/configuration/config-txt/video.md.