There’s a few ways to handle loose parts. The loose hand, for instance, can probably be addressed using a small dot of sticky tack in the joint. That’ll hold it and let you pose it, though it’s probably not going to cut it if you want it to hold a heavy-ish weapon. You can also thicken up joints using a small amount of paint, clear coat, or clear nail polish. Just dab a little in the joint, spread it around, and let it cure completely. When in doubt, use less than you think you need. It’s easier to add more later than it is to remove if there’s too much.

For the arm, double check that the parts are inserted all the way. Some joints have an extra “click” to know when they’re fully seated, and should be marked as such in the instructions. I’m not familiar with that specific kit to know for sure. If you can post pics or describe it in more detail I might be able to be more specific.

If you do end up needing glue, I recommend Mr Hobby Extra Thin cement. It melts the plastic and basically welds parts together. You only need the tiniest bit. Super glue/CA glue will work but it dries brittle and will fog/discolor the plastic.

Edit: looks like there are more comments than what kbin picked up, possibly due to the downtime earlier. Y’all are getting upvotes once federation fixes itself 😁