As per your history, you have noticed cracking of knees (both the knees I presume) for bout 1½ years. It is unusual to have loud cracking at your age. Unless there has been an injury to the knee causing a tear in the miniscal cartilage, which are shock obsorbing crescent shaped cartilages in the knees. Less commonly, you could have a condition from birth called discoid (disc shape) meniscus in which loud clicks may be heard but no treatment is required for this condition unless there is a tear in the discoid meniscus which causes pain.
I think you need to be examined to exclude a miniscal cartilage injury and in case, there is no evidence clinically no intervention may be required in your case. In case the cartilege is torn and that is causing your clicks, surgery may be required.