Why the change?What exactly is your question by circling the MAWS?
On JF-17 Block 1 and 2 (rightmost picture being an example of it), the rear facing MAWS is installed at the base of the tail, while on JF-17 Block 3 (leftmost and middle pictures being examples of Block 3 airframes) the rear facing MAWs is installed at the top of the tail.