i bought Elf yourself app and i bought the 'Soul' theme but i dont know to use it?

i know this is in the wrong catagory but ok,i bought the elfyourself app and i got one theme...but then i purchased the soul theme too..but when i go to it to make a new video its charging me 99 cents when i already bought it...i dont know what to do..i am not gonna waste my money re-buying it..can i only use the theme once?if yes then im gonna remove the app from my phone because theres no point of the app when i have to rebuy a them again!!it should already be there