Tasks stay in calendar after checking! How do I get rid of them?

[AC Question]

Tasks stay in calendar after checking!

I use the calendar a lot for my bills, I will put a task in and then I will put a check mark after its paid. on the s3 and s5 in the calendar the task would stay, but now on the s6 after you check mark it goes away, does anybody know how to make them stay on the calendar? thank you