[Macguru10]

I use a Sony Bravia TV for my computer display. In the older systems, before Sierra, the Display System Preference pane allowed one to shrink or expand the vieing area of a display using a slider bar. Sierra and High Sierra do not have that function.
Upgraded to High Sierra yesterday and lost the settings for my TV display, using HDMI. The result is the menu bar, dock and sides of the screen are moved nearly totally off the viewing area. I can see barely ¼ of bottom of the menu bar, for instance. In the older systems, the slider was a handy tool that immediately fixed that problem.
Does anyone know an app I can get that can be used to resize the viewing area? I tried the display apps in the Apple Store, and all are either outdated or do not have the slider bar.

[Macguru10]

I found a solution by replacing my disply with a newer HDMI display. High Sierra has the slider bar for the new display, but not for my older one.
BUT: the screen screws up on startup, always, elongating 200% vertically. Easy fix; open Sys Prefs again and click on Display pane. Click the Default for this display radio button, and the screen straightens out beautifully. It stays stable until the next restart or cold startup.
Hopefully a future bug fix will fix High Sierra’s HDMI displays bug