Hi Martin,
Is it only on forums that the editor doesn't appear or is it everywhere? Perhaps you could check that the HTML editor is enabled in your profile and also in Administration >> Configuration >> Editor settings.
Text editors
WYSISWYG Editor not showing when editing forum posts
این گفتگو قفل شده است و در نتیجه دیگر نمیتوانید در آن شرکت کنید.