Slideshow Bug or Update?

I wanted to make a tt slideshow of all the birds i’ve photographed recently and wanted to add little captions to each photo but in the black space above or below each photo (because why would i want text big enough to read in the way if my photography) for some reason it wont let me and the text disappears behind the black. does anyone know if this is a glitch or if theres been a stupid update? i know for a fact you used to be able to put text in the area outside the photos since i have some slideshows like that currently posted on my account.