Although dragging and dropping a link is easy, you still need to configure the link. Notice that in the left panel there are four approve/reject elements: ApproveLink, ApproveURL, RejectLink, RejectURL. You can use these four in different ways.
To configure the quick links in your email
In the left panel, click the drop-down list and select Variable Web Link.
If you do not use the Variable Web Link setting, you cannot edit the link properly.
Drag ApproveURL and RejectURL onto the workspace.
You could optionally use ApproveLink and RejectLink, but these instructions pertain only to the URL elements.
Click on ApproveURL.
Under Configuration on the left, change the Link Text to "Approve."