Optical glue. (1 Viewer)

I'm sure lots of people have experienced the rubber grips detaching themselves from camera bodies and these have to be re-attached using a glue that isn't permanent as there are access screws hidden below those rubber covers.
I have two similar problems.
1) The focus ring barrel cover has come off the RSPB 'bins I own.
2) The top menu dial cover that surrounds the shutter button on my Canon 5D3 has fallen off.
Both are usually glued in place.

Any ideas of a ready available product I could stick them back on with. Has to be very secure but not permanent.
Thanks
Dave.

In case anyone else has a similar dilemma of not wanting to use a permanent super glue in case access is required at some stage this is what I used.
For the top dial on the camera I used craft glue spots. They are like congealed glue which is very flexible and as yet has done a perfect job. Hopefully it will still hold tight in the heat of intense sun too. Better than liquid glue as it's much easier to apply to the right place without spilling over where you don't want it.
For the binoculars , again, I raided my o/h's craft box and used a double sided sticky tape which is holding up splendidly.