When installing linux e.g. Ubuntu on a new laptop, the installer might not select/contain the correct driver for the display. This might result in a screen resolution of 600×400 on a screen with Full-HD. Accidentially this resolution is too small for the installation window, with makes it impossible to select and see all buttons. To force another screen resolution while booting edit the boot parameters of grub from set gfxpayload=keep to the following:

set gfxpayload=1920x1080