this is where you gotta go in file explorer to find the sprites.
if you're playing with the skins, go to Boll Tower 0.1.1b\Boll Tower 0.1.1b\skins\player\(insertcharacternamehere) and select the (insertcharacternamehere)hud image.
however if you're NOT playing with the skins, go to Boll Tower 0.1.1b\Boll Tower 0.1.1b\vanilla\character\(insertcharacternamehere) and select the (insertcharacternamehere)hud image. no problem