Hello, a stupid question, i m coming from Fusion360, and i was used that when a dimension is give (example dimater to the circle) then i can move everything else on the sketch, but the diameter is frozen. 
Not in my case. as soon as i click/move the  blue line, then the diameter of the circle change  , meanwhile it s black
and if i had a "Fix" condition, then it does not move anymore but got the warning