Where do I see what changed, and how do I comment?

Activity lists what happens in your groups, newest first, by day: expenses and payments added, changed, deleted or restored, comments, people added or leaving, groups created, deleted or restored, and changes to a group itself, such as its name, notes or cover photo, which show as the group being updated. An edit to an expense or payment says what it changed. Tap an expense there to open it; anything else opens its group, or the friend's page for what is just between you two.

Each expense also says who added it and when, and when it was last edited. Every expense and payment has a History below it, listing each change with who made it, when, and what it changed.

To comment, open the expense, type in Add a comment under Comments and send it. Everyone in the group can read it, and members with Group activity notifications on are told a comment was added. A comment can't be edited or deleted once it is sent.