Date de planification - Manuel utilisateur

Hello,

First of all, thank you for looking for answers in the forum before posting yours. 
It is possible that in 2010, the rules were not the same, but today we prefer that you use English.

As for the planned date, it is the application that manages it and you cannot influence it directly, because it is set according to all your other constraints (resources, availability, FTE, dependencies, actual work...) of your project.

You can however influence the validated date of the project thanks to the global parameter "do not start before the validated start date".
If no stronger constraint prevents it, your project will slide to the indicated date and the planned date will follow.