All you want to do is apply a very tiny dot of glue on the nut to keep it from falling out when doing a string change. If it's a snug fit that doesn't want to fall out, then no glue is required at all.
I don't glue because I'm always fiddling with the things and never totally satisfied. It can slip however which totally knocks you out of tune while playing obviously. You can do like Allen says and have the best of both worlds. The operative word is "tiny" dab of CA glue. It doesn't take much.
I glue my nuts solid to the neck..they are made of ebony, and if they need any work on them or replacing at a later stage in the ukes life it not hard to do ..a sharp cut along the back on the glue line with a blade ..then knock it off with a bit of wood and a mallet.
I fit mine tight and have never had trouble with them moving. I used to put a 1/16" stainless dowel in the center of the slot under the nut, but it doesn't seem necessary.