The lounge is the wrong place to ask. From the day of departure, the ticket will get under airport control and you will be able to go to AF ticketing desks (landside or if you want to change future flights, at CDG also at flight connections) who will be able to change your ticket if you wish, but beware that this will be based on the actual fare conditions, ie change fee if applicable, and difference in fare in any case. In other words, this will likely be an expensive change.

If what you want is a free/nominal fee flight change such as what US airlines may allow on the day to their elite members, that simply won't happen (unless there is a travel incident to factor in, e.g. flight cancelled etc).