can change skin but cant add

ive been scowering the internet for months now, and ive still found no sollution at all. 
nothing at all works

in the minecraft java launcher i can change my skin. it allows me to do that. but i cant add any

this honestly has been annoying me a lot, as ive tried everything i can think of.
restarting the launcher, making it in beta, uninstalling and reinstalling it, repairing it (when you go to uninstall it)

id really appreciate some help and not for this to be marked down as a duplicate of something with no clear resolution