Dear Mr. _denilson,
Thank you for your enquiry.
We can answer your question as follows:
If a player has changed associations, but never played for the other association (youth matches not included as they are not counting as senior caps) he can switch to the other one again.
Meaning, as long as a player has not played for any senior side he can switch associations as long as he wants to. Besides that, a change comes into effect when FIFA approves it.
Hopefully we have successfully responded to your query.
Thank you for your interest.
Kind regards,
*****
Communications & Public Affairs Division
FIFA - Fédération Internationale de Football Association
www.FIFA.com