If you want to upload your Google Drive or Dropbox files from a different account, you can change the linked account by referring to the following:
<Google Drive>
Log in to the Google Drive account that is currently linked to your JANDI.
Once you have logged into your Google Drive, select the Tools icon and click [Settings]. Then select [Manage Apps] and find JANDI on the list. 
Click ‘Option’ next to JANDI and select [Disconnect from Drive]. 
Now your Google Drive account has been disconnected from JANDI. Go to JANDI and connect a different Google Drive account. 
<Dropbox>
Select the (+) icon next to the message box and click Dropbox. 
Once the Dropbox File Upload window pops up, select [Sign Out] located on the left. 
Connect a different Dropbox account in JANDI.