when enlarging fonts, screen surface display is smaller than it should be

[NotYourTypicalDeveloper]

After creating a dummy display for my monitor (2560x1440px QHD), I tried to use the smooth scaling to increase fonts, icon etc .. as all was too small but
either the screen showed as the size of a 24" approximately, leaving a large black frame around the displayed screen
OR
the screen was quite blur (fonts , images everything)
besides, the displays keeps on getting messed up, resulting in me having to go to the settings > displays and re-organizing the positionning of the displays.
Sometimes, the screens are not reachable, meaning that the settings window will remain on a dummy display which I have physically no access and that I can't reach out to as not showing on any of my screens - if that makes sense .. this results to me having to disconnect the dummy displays to gain access to my settings again.

It is definitely not working on my device.
If this is not sorted, would I be able to get a refund for my licence? many thanks

[3DCoded]

Have you tried the new native HiDPI scaling instead of dummies?

[NotYourTypicalDeveloper]

Thanks for the comment. I don't know what it is, how do I enable it please?
I spent the whole sunday trying to fix these. Everytime I touch the settings / try to configure anything in the betterDisplay app or in my mac settings, it messes all my display preferences and reposition the screens randomly. Quite frustrating

[3DCoded]

First, delete your dummy displays, then follow #678 and reboot.

[NotYourTypicalDeveloper]

Hello, thanks.

For this monitor (Dell 27" QHD):
there is no option to set a custom HiDPI resolution, in the Better Display (even though I have the pro version)

On the other hand, for my other monitor (Electriq 27" QHD):

I have added the custom resolution in displays parameters of Better Display for one of my screen (27" QHD)

Now I get these options in the Mac settings. There is no HiDPI for 2560x1440 res. When I pick the 2128x1197 HiDPI resolution, icons and texts appear huge.

Other question: does it mean I shouldn't need to generate any dummy display if I use custom HiDPI?

[3DCoded]

If your display's actual size is 2560x1440, you cannot get 2560x1440 HiDPI resolution. Trying lower resolutions, 1920x1080 should work on that display.
does it mean I shouldn't need to generate any dummy display if I use custom HiDPI? yes

[waydabber]

Hi @cah1983,

the first display is probably connected via a DisplayLink dock which uses a virtual display technology. Native smooth scaling does not work on these displays, you can however use dummy mirroring with them (but it might have issues).

As @3DCoded mentioned, for the other display, I recommend setting an interim resolution (you can go up to 99% of the 2560x1440, but the native resolution itself is not available as HiDPI due to a macOS limitation). I advise you to use the scaling slider of BetterDisplay instead of System Preferences for easier resolution selection. Otherwise you can try clicking Show all resolutions to see more options.