InDesign help auto justify text

Hi, I'll try to explain myself as best as I can because I do not know lots of english InDesign terminology.

I'm trying to add a caption at the bottom of the page where is written the title of the current paragraph that is justified on the left on the left pages and on the right on the right pages. But if I add a page between two pages (thing that I'll need to do often) the text stay justified on the side that it was before.

I wanted to know if there was a way to auto-move the text block if I add a page or if there's a way to add in the master page a text box that write the paragraph text by itself.

Thanks in advance, I hope I made myself clear