Google Sheets on Android and Dropbox - no visibility to Dropbox Folder on SAVE

Not sure what NG to post this in, but here goes here....

I just downloaded Google Sheets for my Android phone that has a Dropbox 
application.  I made the detault app for s/s to be Google Sheets. I can 
open the Dropbox app, and edit one of my spreadsheets, no problem.

But when I got save it (even if I just backout of the application 
wanting the save to occur), Google Sheets is offering me either to save 
the file either "Google Drive" (which i don't want) or "Device".  But no 
where do I see my DROPBOX account under the DEVICE folders to simply 
save it back to where I got it from.

Any ideas how I can somehow tell Google Sheet to replace (or point to) 
the DROPBOX account??
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Regards -

- Andrew