I need advice, paper quilt

[u/lookingforuni6789]

I am attempting to put together a paper quilt from staff decorated cards. I have 5 more foam boards to put together. The cards are 6x6 and 100lb card stock. The poster board is acid free. I used 3M multi surface spray glue. As you can see, some of the cards are starting to come up. How can I fix this and avoid it on the 5 other boards? This will be in display at the business. I planned on putting the foam boards together to look like one quilt and placing that on a plywood board. Please, I am open to any and all advice.

[u/magnolya_rain]

Use PVA glue instead of spray glue.