Use folder rules to manage your files automatically. There are two ways to define rules: create your own rules or link to rules already created for a different folder.
When you define a rule, it only applies to new content added to the folder. Files that were in the folder before the rule was defined aren't affected by it. You can manually apply the folder rules with the Run Rules action.
Note: Even if the folder doesn't have its own rules, it could have inherited rules from a parent folder. A message on the Rules page lets you know if this is the case.