Hi Jean
We don't call this a "deemed" year-end. It's a short fiscal year.
It's not super easy to change year-ends. In fact, it's very complicated, especially if activity was posted in a period that is now in a different year, as is your case.
You should contact your Adagio consultant on the best way to do it. It's beyond the scope of this forum.
If that person needs assistance, have them contact me and I will show them the steps.
Steve