What amp? Head, combo? You don't really need adhesive with heads, at least JMPs. The pot screws hold the faceplate secure enough in my experience. Use a small amount of rubber cement to spot secure it if that doesn't apply to you. Not so much that you would have to distroy the faceplate if you ever needed to remove it.
If it's a plexi plate, the wrong adhesive will attack the paint layers that coat the back of the plate, and may even damage the plastic. I'd try a test patch, just a little dot, of silicone adhesive first. Or you are probably safe with a few pieces of double sided adhesive tape.
For metal panels, you can use just about any adhesive you can get your hands on, if it sticks. Anything from contact cement to epoxies made for bonding metals. But I'd recommend something less aggressive than THAT.
I had a spot that was separating, I used a dab of gorilla glue and it worked fine.... that was around 5 years ago, Its still holding and no adverse effects. But sue extremely sparinig....when it dries it foams up. so use way way less than you first think.