Monitor screen resolution changes when laptop lid is closed

Question

My monitor screen resolution changes depending on wether my laptop lid is open/closed. The lid being open has a lower resolution than being closed. Why is this ?

In control panel I have :

Laptop lid open :

Laptop lid closed :

Answer 1

If you choose to Duplicate these displays, your computer has to choose a resolution that is supported by both displays.

If you cannot choose a higher resolution with the lid open, it means that 1024 x 768 is the highest resolution supported by your internal display. Obviously, this restriction does not apply when using only the external monitor.