Solve the problem that the display of Ubuntu installed on the virtual machine is too small

After installing Ubuntu on the virtual machine, you will find that the display is relatively small

. The first step is to open the settings. The second step
is to find the device.
The third step is to choose the appropriate resolution according to your computer.

This is ok
or use the command to open
the first step xrandr to view and modify it. The resolution of
xrandr -s + resolution_refresh frequency, set the corresponding resolution (for example, xrandr -s 1400x10520_59.98)
and it will be ok