As long your joints are only creaking and popping and are not swollen or in pain, there is no need to worry about anything. Poping and creaking are just normal things that may happen due to several unharmful reasons. If you notice that it mostly happen when moving at a certain angle or after standing for a long time then do some stretching exercise. It mostly happens due to stiffness in the muscles and joints. Stretching exercises can help to reduce the tightness in the joints surrounding muscles.
It is only problematic and a matter of concern when your joints pop from the area of the previous injury. If a ligament heals improperly then also it may pop when you move. Other than that joints may also pop when with age. The knee generally is the noisiest, but sometimes even your hip, shoulder, neck and spine may pop.