First, have you tried clicking on 'Save' in the top right-hand corner?
	If you want to try saving your tree to your computer, follow these steps:
	- 
		On the family you want to back up, click on 'Download/export this family'.
- 
		Select 'FamilyScript'.
- 
		Click 'Download'.
- 
		Save the file which downloads (I recommend in 'My Documents' or equivalent'). Make sure you give it a name you can easily recognise.
- 
		Go to the account you want to export the tree to.
- 
		Go to 'My Account', and click on 'Create or import new family'.
- 
		Click on 'Import GEDCOM or FamilyScript'.
- 
		Click 'Browse' and find the tree's file where you saved it.
- 
		Click 'Import', and then 'Finish Import'.
- 
		Save the tree on the new account (use the normal 'Save' button).
- 
		You should then be able to use the tree as normal.
	Steps 1-4 are fine if you just want a copy on your computer, but you can import it back into your account as a copy by following up to 11.
	Hope this helps!