I connected my laptop to an external monitor for the first time, but unfortunately my monitor is not exactly the same as my laptop. So how do I resize the window on the external monitor. Btw my monitor is completely filled out but it looks like it was zoomed in.
That should be:
Right click on the desktop → Display settings → Scaling and arrangement (a little further down) and then set the "Change size of text, apps and other elements" to 100%.
Right click on a free space on the desktop and select "Display Settings":
In the settings you then select the monitor for which you want to change the resolution and select it.
Then scroll down a little until you find the "Screen resolution" dropdown. There you then set the desired screen resolution (usually the one recommended by Windows).