Recurring Tasks in My Day

Hi

I am puzzled by what appears to be an inconsistent behaviour with To Do in our business.

The behaviour surrounds recurring tasks added to My Day.

When I "complete" a recurring task, the task drops to my "complete" list and the task, in its original list, updates with its next due date. This behaviour I would expect.

I am puzzled because a couple of my team members have what appears to be a different behaviour. When they "complete" the task the completed recurring entry drops to the complete list, in the original list the task updates with its next due date BUT the "new" task then automatically appears back on My Day. 

I feel sure that this must be down to a setting but I have not been able to find it. All versions of To Do are the same.

Can anyone point me in the right direction please?

Many Thanks

Neil