Selected item not outlined. Rotation gizmo shown instead Somehow I have entered it a mode where a selected item  is not outlined. Instead, the rotation trackball gizmo is shown. How can I get the outline visible again?I have ticked the box: "outline selected".

See attached screen dump. I have selected the TV and  the rotation trackball is shown.
See on the left side of the viewport, where the toolbar is?

The one highlighted in blue is your selected tool, the scaling tool. Instead, select the very top one with the picture of the mouse. That is the selection tool, and it will give you the default behavior.