HI Silvin, Thank you for your question. I understand that between two Mac computers that bookmarks are not syncing. In order to make sure that both devices are connected to the same acocunt and the same version please get both computers and try this experiment: For both computers do this #Go to the sync page and click disconnect account #Go to accounts.firefox.com #Sign into your account from here #Click on Tools > Sync now #wait 5 mins #Do this again with the other computer #Add a new bookmark to one of the computers #Click Tools > Sync now on both computers # Search for the bookmark on the second computer Is it there?