The resolution depends on the hardware device, the pixel density and overall size of the display as well as your graphics card abilities determine the overall resolution.
Some graphic cards support only a limited maximum resolution such as 1024 or 1366, If you still need to change the resolution manually which your hardware card does not support, you can do it manually in Ubuntu.
- Settings > Display > Check your current resolution
- Then edit your profile file inside `gedit ~/.profile`
Finally, you can logout and login again you will see the resolution in your settings.
You can even try the above command in your terminal.