thanks for those tips CleverCat

The UI is very confusing here:
under the 'View' tab, you can view all of the documents you have uploaded to SpiderOak. Documents which have historical versions saved will be followed by a number in parentheses which indicates how many historical versions SpiderOak has saved. They will look like this: file.doc (3) To delete any of these historical versions, click on the file, and SpiderOak will open another window to the right showing you all of your historical versions, the date they were saved, and their size. Simply select any of these files and then click the 'Remove' button to remove them from your account. (To select multiple files, just hold down the Control key and click which files you'd like to remove.)
The way it's phrased (in the message-box shown on clicking delete - see below), is confusing - it talks about the file/folder as opposed to the revision, so I thought it was not connected - but now I know


With SpiderOak 9713, you can prevent historical versions from being backed up by going to 'Preferences' in the client and under the 'Back Up' tab check the box that says 'Don't archive folders older than' and then enter your preference.
in my version 3.7.9781, the option is "Don't backup files older than:[ ][hours/days/etc]"
again, I'm not sure what exactly this means -
e.g. if I choose 3 days, does that mean it will keep revisions of a file for a period of three days prior to the last modified date of the file,
or, is it going to delete -or refuse to backup- everything older than 3 days, or...

I guess I should be asking these questions of SpiderOak but I'll throw them out here first...