Tool bars won't go away...

I have a file that opens in fullscreen like it should.

Clicking on an icon opens a new page in the document in fullscreen, as it should.

When I clcik on the red X to close that page, it should go back to the first page, which it does, but now the toolbars appear, instead of being fullscreen.

What do I need to do to get it to open fullscreen instead of showing the toolbars?

Thanks for all help!