Strikethrough vs. Checking off and event disappears in Calendar history....PLEASE HELP

[nathenao17]

I upgraded from a S4 to S6 Edge and I used my calendar very often. I like the fact that my S4 was able to check a task off and strikethrough the event. My S6 Edge does not do that. Apparently, the event disappears after checking it off. Please help! Hopefully, I am simply overlooking a setting or Galaxy needs to update their calendar. I have many other issues such as disabling read receipts, disabling preview in my text messages and so forth. I'll create another thread for my other issues. Can someone help me?!