How to change file family

Do you mean change the organizer? To change Organizer you have to disband the current family and set up a new Family group with the different Organizer.

How to leave Family Sharing --> How to leave or remove a member from a Family Sharing group - Apple Support

How to set up Family Sharing --> How to set up Family Sharing on your iPhone, iPad, or Mac - Apple Support

Hello,

Sorry, but what do you mean by "file family" exactly?

Are you trying to leave a Family Sharing group and join another one?

Are you trying to change something about your family sharing group? A setting? A shared subscription?

Please explain clearly and detail exactly what it is you are trying to accomplish.