no it didn't work because when i do this, that creates a new sequence ! it is not what i want.
all my footage is already feautred, i can't do it again.
thanks but, since the problem, i managed to solve in different way my issue : i selected one by one each clip, then right mouse click menu, then select "scale to frame size". Premiere is intelligent because it didn't rescale, (where i expected pixelisation problem) but it re-used my original clip (which are in the right resolution expected).
The result is pretty good, i am satisfied :
have a good day
For the future you may want to do this:
Go to Edit, Prefrences, and tick default scale to frame size.
thanks, this helped me