Since the recent updates, my Thunderbird has gone bonkers with confusing settings. I have lost all my previous settings and in particular cannot create any subfolders. I have had no problems in the past. I have tried a few solutions suggested by other subscribers without success. It would be greatly appreciated if the developers (who have done a marvellous job for so long) can rectify the problem ASAP. Otherwise, can I revert to an older version?