I'm using a rPi 4b with retropie version 4.6.7 on an old CRT TV. Because certain menus can be challenging/impossible to read in Retroarch with the default theme (XMB I think?), I've changed the theme style to RGUI, as it's large, clear, and legible with my limited resolution.
RGUI is the default in retropie. did you delete any .cfg files? please fill out https://retropie.org.uk/forum/topic/3/read-this-first?
but then in the following emulators it appears as the default that I can't read (XMB I think?):
again, suspect you've deleted or messed with .cfg files. please provide a verbose log for these, as per my above link.