Hello , my name is Jack Perhaps I can help you with this problem but first i would have a few questions;
Is your laptop connected to the tv using a VGA cable ?
with an HDMI cable
O.k then your tv does not recognize your laptop as a "PC" and does not offer the option to adjust the screen size beside the ZOOM button on the remote which I doubt would set a correct screen size although you could try it.
If you`d like to have full control over the computer mode display then you would need to connect it with a VGA cable then in the OPTION menu under VGA SETTINGS you would be able to set it either to AUTO or to adjust the horizontal and vertical size manually .
My laptop will not allow the use of a VGA cable
Sorry then but perhaps the only options left would be with video/display software through your PC .
Some video cards /chips have their own specialized software that allows you to set the screen size and resolution .
Possibly that changing the resolution on your pc may help as well ?
Afraid that this tv was made to be used as a monitor only through it VGA input.