External display doesn’t fill screen

I’m using a Mobile Pixels DUEX PRO as an external screen for my Mac laptop, and at normal resolution, everything is too small (see first picture). I’ve tried to change the resolution, but all that ends up happening is that the screen scales down but doesn’t fill the screen, and everything is still way too small to read. (second picture) How do I decrease the resolution of the screen while still having it fill the screen? Thanks!

To clarify, I'm not looking for how to “zoom” using the accessibility settings, the issue is that basically everything on the external display is half the size of what it is on the main screen, and the “scaling” option in display settings doesn’t actually change the resolution of the screen, it just decreases the actual size of the screen.

As for info on the screen, it’s the Mobile Pixels DUEX Pro, which connects via USB (here: https://www.mobilepixels.us/pages/duex_pro_product_page). I’m on Mac OS 10.15.2, and the driver for the screen is DisplayLink. My laptop is a 2014 Retina MacBook Pro.

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Something is odd with the display - I expect you to have the traditional larger text / more space controls rather than a list of resolutions.

The resolutions are poor for controlling text size as you correctly have diagnosed.

Your OS is totally up to date and your hardware is well capable of driving that display. Does the vendor have an update to the display / firmware you might load to assist in working more like most display port monitors? Your Mac can use an iPad to run display, but since you already have this hardware - I hope my start to an answer either helps or someone can provide the clue / missing step to get back to the controls above.

One hint - when you are in the displays preference pane and your DUEX is connected - hold the option key and down by the help question mark - bottom right, you should get a button to "Detect Displauys" - press that once and exit out of displays / re-enter it to see if that helps get you different choices.

I would also check "Show mirroring options..." so you can see if the menu item for the second display helps you mirror / change the resolution.