Cloudberry makes a huge file Are you not getting the Windows UAC prompt after you select the new folder? A UAC prompt should come up asking for elevated permission to change the folder. If it's not coming up, have you disabled UAC in Windows?
The other option for you is to open an elevated Command Prompt (type CMD in Start Menu and right-click the Command Prompt entry and select Run as Administrator). Then type in the following:
cbb option -repositoryLocation PathToFolder