Knee making popping sounds for yearz without pain

I'm a 24-year-old male, and my knees keep making these popping noises every time I walk down the stairs. It started in my left knee, and I just recently found out the right knee does that as well. They never hurt at all, but the sound it makes is quite annoying, and I'm afraid that one day it could lead to something.

I've been pretty healthy and active, working out for the last two years. I also used to be a footballer for years, from childhood to early high school, so I've been using my legs without any problems until about two years ago, when the popping sounds started. This was around the time I started doing resistance training.

I'm sure my legs are pretty good because I've hiked four mountains this year without a single issue with my legs, but the noises always annoyed me, and I would very much like for the popping noises to disappear.

Any idea on what it is and how to get rid of it?

Thanks for reading