4yrs ago dislocated knee sitting in a chair and x-rays done to search for break, none now both knees hurt all the time feel like gunna lock?

Have them evaluated: I am not sure how one dislocates a knee sitting in a chair. Have the knees evaluated either by a rheumatologist or orthopedist.

Knee locking: The x-ray would not reveal a soft tissue injury, like a meniscus tear, but an MRI of the knee can. A meniscus tear may explain why your knee is locking. The tear can worsen as menisci have poor blood supply centrally. It may undergo degeneration, develop arthritic changes and cause more mechanical problems like giving way due to joint instability and add stress or injury to your other knee.