New glass not sticking well.

I replaced the glass/digitizer on my iPad Mimi 2 & all went reasonably well. Everything works properly, but the glass keeps popping up in a few spots. I was very disappointed in the instruction video as it made no reference to cleaning off the old adhesive or any instruction about reassembling the unit. It is not as simple as reversing the removal process! This unit may have some damage to the case, so the glass may be lifting because it is ever so slightly bowed??? Never the less, the adhesive doesn’t hold very tightly. Makes me wonder if it should be heated to make it stick better? Judging by how difficult it was to remove the original glass, this replacement adhesive is nowhere as strong. Should I reheat the edges to get the adhesive to work better?

Thanks,

Kev