I have a 32 inch monitor with a resolution of 3840 x 2160, Framemaker 12, and the size of the icons in the menu bar is microscopic

What version of Windows?

Does your mouse have a scroll wheel?

If so, try holding the keyboard Control [Ctrl] key down, and rotate the scroll wheel.

IIRC, the standard icon sizes are 18x18 pixels and the large ones are 26x26 pixels. These were designed before 4k monitors were readily available, so you won't be able to make things larger in FM unless you use something like Windows Magnifier (see: Make items on the screen appear bigger (Magnifier) - Windows Help)

You should put in a feature request to add icons for 4K monitors. See: Bugbase & Wishlist

> Ctrl and mouse scroll only increases the document size.

Yep. If you click on the Windows desktop, it controls icon size there. It either does nothing to inform any apps that you run, or they aren't listening.

> I have no problem like this with Versions 10 and 11.

How do they behave differently?

Your display has a native resolution of 139 ppi. That's highish compared to historical desktop displays (which typically ranged from 60 to 100), but of course is paltry compared to cell phones and tablets today, many of which are well over 300 ppi.

For the first 20 years of PCs, few dared to introduce a monitor with a dot pitch much below .25 mm (102 ppi), due to the short-sighted hard-wired icon sizes and dialog text fonts in operating systems. I had a .22 mm CRT for several years, and simply couldn't run it at its ideal resolution. Sony showed a .15 mm Trinitron at COMDEX one year, and never brought it to market.

Apple moved beyond this (and is about to roll out a 5k "Retina" iMac). Microsoft is only just beginning to catch up. Many Windows apps are still stuck in the 20th century rez-wise, and it's not clear that Microsoft has any effective OS tweaks to work-around in-app icon/legend/dialog limitations. I consider the Retina branding to be mostly marketing BS, but what it does clearly bring to the table is elimination of scaling artifacts when legacy raster content is re-sized at arbitrary values (on lower resolution screens, you're pretty much limited to integer multiples and fractions for scaling).

> You should put in a feature request to add icons for 4K monitors.

Put that way, the request is apt to be ignored. FM already runs on "4k" monitors, and the icons are probably of adequate size on a 50-inch 4k monitor (or a multi-monitor setup approximating that).

The issue is icon, legend and dialog text sizes on high resolution displays, irrespective of raster pixel count and screen diagonal size. What might suffice is another maker.ini setting like Monitor Size (supported by a Preferences or Options dialog for extra credit).

So I'd put in the feature request for "useful control of icon, legend and dialog text sizes on very high resolution displays (120 ppi to 400 ppi at least)".

Aside: the Monitor Size setting in FM appears to control only whether a 100% display of a document is actually at paper size on screen. It has no influence on icons, legend and dialogs. In the old days, before GPUs were fast and cheap, it was actually useful to tweak the mon size so that, at your preferred edit scale, for imported raster objects, one source object pixel took one screen pixel (or integer multiple/fraction thereof), as doing so improved display performance substantially.