Please, turn off native Synchronization of bookmarks in Opera and Firefox, then try again.

Для выбора поисковика можно пользоваться аддоном Live Start Page https://addons.mozilla.org/en-US/firefox/addon/live-start-page-lst/

try to reinstall addon. Also tell us your OS and browser version.

Do you have Chrome sync off? 

How many bookmarks do you have?

В настройках можно отключить. Как браузер используете?

Do you use EverSync synchronization? Have you turned off Opera and Firefox native sync?

Please, leave us the link to the theme you want to add.

You probably talk about dials preview images auto update. Turn this function off in setting, but keep in mind that all dials must get their preview at least 1 time.

Google Translate: Vous parlez probablement de molettes de mise à jour automatique des images d'aperçu. Désactivez cette fonction dans les réglages, mais gardez à l'esprit que tous les cadrans doivent avoir leur aperçu au moins une fois.

Please reinstall addon in this case. Ok check for updates. We've updated it recently and added this button