To do so, go to your privacy settings (click the arrow at the top right of the homepage to get there) and then edit your "Timeline and Tagging" settings.
If you really, madly, deeply want toedit your docs, there's one way to do it -- click on the share button on the top right corner and choose "Open in Safari" to pull up the Google Drive web app that's been available on iDevices since the service launched.