For small screws I was under the impression purple Locktite, 222ms, was the proper choice.
Always has worked good for me.

I have used medium, the blue, for nearly everything. I use too much and I have never had an issue removing anything or anything coming loose. Never tried purple but I see no use. I have one tube of permanent, red, which I think I used once on a sloppy fitting sight blade if I recall. It did not come loose. Lol