To the best of my knowledge Mycelium has exactly two backups. One is the HD wallet backup, consisting of the 12 seed words that you should write down manually on a piece of paper.

The other is the backup for all non-HD accounts. It is a PDF file along with a passphrase that should also be written down manually.

Once you have successfully done these two backups, everything you have in Mycelium is backed up securely.