By clicking the three dots on the timeline you can edit, move or delete an entry.

You can change the length of an entry by clicking on the striped area on a period in the editing view or any empty spot in the right period. You can shorten the length of an entry by clicking on the minus –sign on a period.  

To move an entry, tab the tree dots, click Move course

click on the striped area on a period where teaching is offered.

The course has moved to another period.