1) Select -> object properties or select -> object properties tree (the second option has more settings, but it is less convenient).
2) Select the quest building and, in the object properties tree, configure the task as if it were the main one. To make the royal mausoleum work, you need a script with a trigger that activates when the object is visited.
3) Select and press the delete key.
4) Go to the object properties tree and change the corresponding property (it seems to be rotate). Keep in mind that for objects larger than 1x1, rotation may not work correctly.
5) You just needed to check our file archive: /files/10086/>