depends on the mode you are using for "All".
the category menu has an advanced option to allow the user to select very few check boxes by "doing the contrary".
if you want to hide only ONE category from a list of 500, instead of selecting the games you want to see (marking [√] 498 times) you can select the games you don't want to see (only one [X] !)
• if ALL has a [X], it's exclusive mode.
it displays ALL games, except the ones with the category marked as [X] (forbidden).
this mode has no effect on the [√] (enabled) and on the [+] (required) categories.
• if ALL has [ ] no mark, it's inclusive mode.
it displays ONLY the games containing the categories marked as [√] (enabled) check mark, but not the games containing the categories marked as [X] (forbidden) mark.
In the same spirit of not marking 498 games manually, there's a way to easily forbid a lot of categories at onces (instead of marking X to all categories you don't want), it can also
not display the games
not containing a category set as [+] (required).
if there are mixed [+] and [√], only the [+] are processed. (too much work and cpu process to do both)
• if ALL has the [√] check mark, it displays ALL games (bypass any category filtering, to allow the user to find and manage all game's category easily)
(note: you can't unset ALL from the individual game category menu, or it will defeat the "display ALL" purpose)
Full tutorial here
https://gbatemp.net/threads/usb-loader-gx.149922/page-778#post-4251265