Formulas not present in office and sort dates in pivot table

Hi,

I have a membership for office 365 and want to use the formula =ifs (als.voorwaarden in dutch), but the formula is not present in the program. Any idea how to solve this.

And I have a problem in my pivot tabels. As I want to sort dates from old to new.

Tried all solutions I can find on google. But dit not solve it yet.

Hope you can help me out.