If I understand the issue correctly, it sounds like your husband signed into Firefox Sync on under his own Firefox Account and that caused the system to merge your two sets of bookmarks together?

If that's the case, you need to sign out of Firefox Sync from the Firefox settings page and then delete any unwanted bookmarks. If your bookmarks are now appearing on devices that your husband is signed into, it's because the Firefox Sync service is supposed to sync all of your bookmarks across all signed in devices. Since your husband signed into his account, the system sees your bookmarks and assumes that they are newly added ones that need to get synced.

If your husband doesn't want your bookmarks on this device(s), he should be able to delete the unwanted bookmarks on one of his devices and then the changes should be mirrored across all devices. Just make sure that you have signed out of his account on your device BEFORE removing any bookmarks or else any bookmarks they he deletes from his device could also be deleted from your computer.

As a side note, do you and your husband frequently share the same device? Do you want to always keep your bookmark separate from each other?

If you do, you may want to look into setting up a second profile folder for your husband to use on your device. This will make all of the settings and other data on your profile entirely separate from your husband's profile.

Hope this helps.

Are you both using the same computer (device) or is this happening with separate devices?

If this is the same computer then do you have your own Windows user account?

Thank you for your help. I wish i realized before.