If your knees click pop, grind or feel stiff and achy when you go to sit down and back up to standing, there's an easy fix for that.
Your body wants to keep your feet under your hips when coming up to stand and back to sitting down this way. When your shin is angled forward and your knees are in front of your toes, it puts a lot of friction on the back of the kneecap. The back of the kneecap doesn't like that.
If you can keep your shins vertical as long as possible (use the armrest if you need to) and leave your butt back in the chair when coming up to stand, it will feel better on your knees.
When you go back to sitting, keep the shins vertical, reach back to the chair if you need to, and then sit down. By keeping your shins vertical you protect the back of the kneecap against too much friction.