Please note that, when taking an age-related squad from one season to the next, you DO NOT have to create a new squad.
Simply enrol your current squad into a new season by hitting the Season tab, creating a new season with the relevant age group, then hitting the Competitions tab and setting up or selecting the competitions that you are entering next season.
All your Club, Squad and Players details will remain unchanged and you will be able to access all of your squad's historical details.
Remember: do NOT set up a friendly as a competition! You can identify a game as a friendly when you create the fixture.