You can save a backup of the profile on a thumb or external hard drive.

Back up and restore information in Firefox profiles {web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.

Sync isn't meant to be used as a backup, but is meant to Sync data to other devices. You should always backup your personal data yourself locally.

• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

For the bookmarks in particular:

• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
• https://support.mozilla.org/en-US/kb/import-bookmarks-html-file

• https://support.mozilla.org/en-US/kb/restore-bookmarks-from-backup-or-move-them

• https://www.ftc.gov/tips-advice/business-center/guidance/complying-coppa-frequently-asked-questions-0