Calendar app archiving events after just a month

Recently I have only been able to go back one month in my Calendar (Outlook for iOS on iPad) - previously there was at least one year’s worth (possibly more).

As far as I know I’ve not made any changes. Almost everything I googled said “Go to the file tab then .....”, but I can’t as I’m using the app and there is no file tab.

Can someone please tell me how to display all my old events and appointments?

Thanks, John.