I find the same problem, Carey.
Has anyone found a way to change the folder, or does this need to be carried out by a reinstallation (and selecting a folder other than the default)?
I wasn't able to use BT Cloud as my sync folder as it was deemed to have been selected as a backup folder. So I had to create a folder, BT Cloud (1), copy the folders I wanted to sync to it (including My Documents, for which I needed to set a pointer so that it would be the default Documents folder). You could possibly set My Documents as the sync folder directly (in BT Cloud Preferences) but then all documents in that folder would be synced, and nothing else.