UI Oddness

I have two PC's running Win10, with the same download of Resolve14 installed on both.

On one, I can set the Single Viewer Mode,.... on the other, the option's not present.

One PC is an Intel NUC with single screen, the other is an x58 based i7 with two screens.

Anybody got any idea how to get the Single Viewer Mode when it's not showing up in the menus?

UI setup depends on your actual working resolution and gui mode (single / dual screen mode).
If both are the same they should both have that option. If not it can differ, small rez screen have different optios then high rez screens. But first i suggest you use the menu option "reset GUI layout" at least 2-3 times (sometimes 1 time is not enough) , which resets the gui to its default settings for the active screen resolution and layout. Sometime needed after upgrades or resolution switches etc.

If nothing works show a screenshot and specify your resolution so we can check what you should see is what you see.

I'll give that a shot.
The PC that does show that option has a 24" Benq screen running at 1920x1080
The other has a pair of Dell 17" LCD's that IIRC run at 1366x768, same as my laptop, which also doesn't show the Single Viewer Mode.
The laptop has Win7 and Resolve 12.5, the PC's are both Win10 and Resolve 14.
That seems backwards to me, as lower resolution screens being forced to show smaller preview windows, is just annoying.