Question: I've got a monitor which has a resolution of 1920x1280, but I can't enlarge it any more than 1024x768. So everything is a bit too large. How can I change the resolution in my case? I tried in terminal with xrndr too.

Answer: 
You need to find out why your system not able to detect your monitor resolution properly, likely due to your display drivers.

Anyway, the xrndr workaround involves few steps - see if you missed out any.

* Calculate mode lines

`$ cvt 1920 1280`

* Create the mode lines from above

`$ xrandr --newmode "1920x1280_60.00" 206.25 1920 2056 2256 2592 1280 1283 1293 1327 -hsync +vsync`

or

`$ newmodecmd=$(cvt 1280 1024 | grep "Modeline" | sed -ne 's/Modeline/xrandr --newmode/p')`

`$ newmodecmd`

* Add the mode to your display

`$xrandr --addmode VGA1 "1920x1280_60.00"`

* Activate the mode.

`$ xrandr --output VGA1 --mode "1920x1280_60.00"`
```
xrandr -s "1920x1280_60.00"

```

worked for me