I have tried to change the default path for docs via Tools > Options > LibreOffice > Paths > My Documents, but this only seems to be affecting Text docs. How do I remedy this so that it affects all docs, including Calc, Impress, etc?
Did you make sure you opened LibreOffice so that just the “shell” is showing? Screen should look like this:
If you then go to Tools > Options... > LibreOffice > Paths, the value you enter should “stick” for all applications (Writer, Calc, Impress, etc.). This, at least, is how it works for me! (Ubuntu 13.10, LibO 4.1.3.2)