The change in point is the difference between the last (8th) round and the 7th.
So, in the round 8th Ahad had -1 points and in the round 7th, Ahad had -6 points.
Then, the difference is:
Difference = -1 - (-6)
Difference = -1 + 6
Difference = 5
The change in points in the most recent round is 5