Each time I want to go in that space (parameter or setting, sorry I’m french 
) They ask me for a password that I don,t remember and so, I can’t never login to make changes…any Idea ??
Please ask your question in the French section.
It will be easier for you to explain your exact problem.
https://forum.avast.com/index.php?board=23.0
If you want to remove the password you will need to perform a clean installation of avast.
https://forum.avast.com/index.php?topic=169255.msg1203279#msg1203279