From someone who found out the hard way (a long time ago on an old radio) that Philips and Pozidrive are not the only cross head screw standards get a set of JIC screwdrivers!
Only thought on nail polish vs loctite, nail polish is a cosmetic treatment, loctite is an engineering adhesive made for this type of application, either remove the screw completely apply by touching the screw thread to a drip of loctite on a surface such as a bit of masking tape, or dip a cocktail stick in to the same drip and apply to loosened screw.
I always prefer to apply to the thread not under or on the head, but that may be sufficient for this application.
If you are going to remove the screw completely do it with the lens stood on its end so that if the mount has shims under the screws they won't slide out!
When you tighten the screws, be sure to use the right screwdriver, those heads are not Phillips, and can be messed up with a Phillips. You can't tighten it properly with a Phillips, since the bit slips.
Get a JIS screwdricer (Japan Industrial Standard). Then, you can torque it down properly, and a little locktite works great. Don't use nail polish.
*shrugs* Nail polish works better for people who aren't used to applying the stuff, because it starts out thicker than Loctite, and therefore is less likely to drip where it shouldn't. Like on your lens glass.
7DII+Grip, 7D+Grip, 40D+Grip, 5D+Grip, EF 24-105 f4L EF-S 17-85, EF-S 10-22, EF 70-200 f2.8 L IS II, EF 2x III, Σ150-500, Σ17-70 f2.8-4 C, EF 50mm f1.8, 550EX, Triopo TR-985, Godox FC-16, Filters Remotes Macro tubes Tripod heads etc!
5D, 20D, 24-105, BG-E4, BG-E2N, 17-85, Nifty 50 pre owned. 😀