When you connect your Google Sheets to Geckoboard via Google Drive, you can indirectly give access to your Google Drive spreadsheets to anyone else invited to your Geckoboard account. This can become an issue if there are spreadsheets you don't want to share.
One solution is to create a direct download link to your Google Sheet, which will allow you to continue updating your Google Sheet as before. First you'll need to to enable sharing on your Google Sheet.
Click the Share button in the top right hand corner.
In the Get link panel, set your spreadsheet file to be visible to 'Anyone with the link'.
Click Copy link to copy your sharing link.
Switch to Geckoboard and edit a widget powered by your Google Sheet.
On the edit widget screen's breadcrumbs menu, click the downward arrow beside the name of your widget.
Click Change spreadsheet.
From the Choose File menu, click on the link icon and paste your sharing link URL in the Link to file field.
Repeat for any other widgets powered by this Google Sheet. You can now continue updating your Google Sheet as before and it will automatically sync with Geckoboard via the generated link.