Screenshot your desktop, please.
I'd guess that you've done something where you've squeezed the bottom of your application frame up, in order to be able to see the desktop on a Mac system, but without further information it's not possible to tell.
Generally speaking, opening images in Tabbed mode, with the application frame covering [most of] the screen, will accomplish what you want.
The only other suggestion for workaround I can offer (coming from one who cannot directly influence Adobe to change their mechanisms) would be to move the Tools Panel over to the right edge so that you eliminate that overlap at least.
For what it's worth there was a time I preferred windowed operation and didn't want to switch to tabbed view (with application frame, which is always on for PC users), but a glitch in a 3rd party plug-in back in the time of Photoshop CS4 that broke operation in windowed view forced me to use tabbed view for a few weeks, and surprisingly it grew on me in that time. Ever since then I've preferred it as it smoothes over a number of the little issues that plague windowed view.
It's pretty clear Adobe would like to herd us all into using tabbed view with application frame on, and they have polished that combination up.
All that's wrong is your toolbar is floating. Dock it to left edge of screen so doc windows will not open behind it; drag the bar by its handle, to the left and below the Options bar, until the left edge of the screen turns blue, and release the mouse button while blue.
1/16" makes a difference-- Thanks, Conroy! Reset my workspace, and at least that part's resolved.
Thanks, Noel. Tabbed view is any easy switch, but that app frame would take some getting used to. I'm always shifting from LR to PS to desktop-- thank goodness for hot corners...