With other pngtuber software the costumes/states can be changed regardless if the window is selected or not but this software i can only change the costume/state if i select the window first, is this just my computer or is it like that for everyone? Thanks!

From the official tutorial:

The costume hotkeys don’t work when not focused on the program
This is a limitation in godot. Godot is made for games, so it doesn’t make much sense for a game to be able to read inputs if you’re not focused on the game. There may be some code that could fix this, but I’ve yet to find a solution.
See if this works idk