Good answer, thanks.

More info:

"You’ll know Track Changes is on when you see it in the status bar at the bottom of Word Online." from https://support.office.com/en-us/art...5-183049F90BD8

"In addition to adding new comments, you can view existing comments to delete them or reply to them." from: https://support.office.com/en-us/art...rs=en-US&ad=US