How do I change the header in a page from selecting image on another page

I am working on a multisite that will allow each site administrator the option of selecting an banner image to use for headers on each of their pages (the headers can be different on each of the pages). These pages are from the same page template I created so I can manipulate the page pretty easily. I have created a button that shows on each of their pages for admins only that will take them to a banner page (and it passes a parameter to that page to show what page sent the request). I have created the page that has the banners shown and I want them to be able to select which banner they want and have it update the banner on the page they came from (the parameter that was passed will tell them which page). I'm just stuck at figuring out how to pass it back to the page to change the header and make it stay unless they choose to change it again. I figure I'll set a variable for the image src but not sure how to set that variable.
Would it be best to somehow set these image paths in a database table and do a select from that table to set the variable or is there a different way to go about this?
I think I will work on the custom database table option for now but wanted to bounce ideas off everyone on here to see what they think is a good option.
I will let everyone know if I am able to solve it and what method (and who it comes from) works out the best.

Thanks in advance.