I use laptop on multiple docking stations with different size of external display monitors. When I switch my laptop to a docking station with lower display resolution (from 4K monitor to 1600x1200 monitor), UE automatically increase the font size from 10 to 15.

My comments/suggestions are:
1. When you switch to a display with lower resolution, UE should decrease the font size, not increase. Low resolution monitor already makes everything look bigger. It does not make sense for UE to increase the font size.

2. Can the font size to be locked so that UE will not change font size according to the resolution of external monitor ?

Perhaps you should check your Windows Display Resolution settings. Since Windows 8.1 the user is allowed to scale DPI on a per monitor basis. However it is not immediately apparent that you can do this per monitor. There is a slider bar to change the size of text, apps and other items with a minimum of 100% and the maximum is determined by the resolution of the attached displays. The setting shown affects only the monitor that is highlighted as the active monitor. To change the DPI scaling for the other display it must be selected first and then move the slider. The change requires an account logout and login to take full effect. Failure to do so may result in controls accidentally moving off the end of the screen and becoming unavailable to click on. That can be very bad if you don't remember your keyboard shortcuts.

Since you mention that you attached to several different external displays as your second monitor, You should adjust the DPI scaling for each monitor each time you attach to that docking station.

In the event you have a version of Windows older than Win 8.1 or Win 10, then only one DPI scaling is allowed, which you set from the Display option in Control Panel. The older versions of Windows allow three choices, Smaller-100% (Default), Medium-125%, and Larger-150%. If you set this value to larger on the 4K display to make the tiny text easier to read but then moved to a lower resolution display you would get oversized text on that display.

Note that you may also have separate DPI scaling on your video card as part of the driver software. If your docking stations have a their own video card built in instead of using the laptop's video, that would be another place to look for settings.

It may not be an intended effect. You will think that the font size setting should be saved somewhere permanently and won't change even if hardware changes. This effect may not be noticed by most people probably because most of the users don't dock their laptop between home and work (two different size of monitors). It is not really a big deal.

The following effects has been consistently happening on my laptop:

1. Connect my laptop to a 1920x1200 monitor (work), set the font size in UE to "Consola 10", close UE, shut down laptop.
2. Connect the same laptop to a 3840x2160 monitor (home), start Windows, open UE. The font size now shows "Consola 7"

3. I change the font size back to "Consola 10" again. close UE and shut down pc.
4. Connect laptop to the 1900x120 monitor (work) again, start windows, open UE. Now, it shows "Consola 15"!

I noticed that the font size won't change if I am switch between two monitors with similar resolution. I tested it by connecting the same laptop to a 1280x1024 monitor at work and a 1920x1200 monitor at home. The font size in UE did not change (which is good).

Maybe it has something to do with my 4K monitor? Could a super high resolution hardware (3840x2160) mess up the setting in UE?

font size for the document window area (i.e. the text in the file got bigger or smaller).
Menu/toolbar everything else are fine.

The size of the "screen font" is probably dynamic depends on display DPI.

I'll ask IDM. Thanks.

I'll check my 4K at home with other resolutions to see if there is any difference in font display. I'll also check my second monitor which is standard HD. I don't have a docking station for my laptop so can't check that. I changed laptops last year and haven't hooked up an external monitor to the new one so I need to check to be sure my laptop can run my 4K display at full resolution.

MickRC,
Thanks for trying and testing. Since it is not hard to change the font size back, I am going to leave it along for now.

There is no other process. I think the different DPI among the screens (laptop, home monitor, work monitor) may have contributed to the problem.
I did a search and found one article saying that applications that are not DPI-aware could have some problem of auto-scaling, see https://msdn.microsoft.com/en-us/librar ... 84173.aspx

It is similar to what I saw - when I switch to a high-DPI (150 DPI) 4K monitor, the font size of the Menu/Tool Bar are fine, but the font size in 'file-tree view' and 'editor (text area)' windows sometimes become too small.

I'll do some more tests.

Once user set the font size in View -> Set Font , the setting should be saved and should not be changed regardless screen size. I don't know why the font size setting keep on changing every time I connect to a different screen. This is not about the visual display - this is about the font size setting. UE automatically change my font size every time I connect to a different monitor. I have to go to the View -> Set Font to reset the font size.

If I go to View -> Set Font and set the font size to "10", I expect that the size remain "10" no matter what monitor I use.

I took the plunge at home and upgraded my personal copy of UE to v23 this weekend. On my 43in class 4K TV/Monitor the display is good. The ribbon icons are perhaps a bit large but I will see if I get used to them and the ribbon itself before I go back to the toolbar. If I did more coding at home I would be back on the toolbar if for no other reason than compatibility with my work environment. Well, maybe not, because I just found out that the work computers should be upgraded to UE v23 in the next 2-4 weeks. It all depends on how busy our IT department is. They are rolling out a newer MS Office to all of the computers so our upgrade is a lower priority.