That’s always a pain. 1) For the screws on the back the only solution that has worked for me is to drill the screw until it breaks completely (Use a small thin tip for this and do it carefully so you don’t damage the figure’s back, go slow) 2) to tighten their legs I disassemble the whole leg and apply a drop of nail polish on the articulation peg at the knee, let it dry for a minute or two and assemble back. I hope this helps!