I have an Acer Aspire 5745-6492 with 15.6" screen. I work with multiple documents, so I got an LG E2240 monitor. The display seems fuzzy. I disabled the laptop monitor, which seemed to improve it, but it doesn't go to 1920x1080 resolution setting. The closest I get that works is 1280x1024. At 1600x1200 or 1820x1440 I get a message saying it won't work. Suggestions to fix this? Do I need an new video card?
Resolution is limited by the video card. IDK if you can actually replace the video card inside that laptop, as space-limiting issues always occur. If you can, then good, albeit it will not be an easy process. If not, try matching the monitor's resolution to the laptop.
The laptop's screen has a native max. resolution and you can not crank that up. The video card may be limited to that resolution by the manufacturer, since the screen can not do anything above that. If you can upgrade the video card, you need to make sure the new one will support higher resolutions, and also that the highest one matches the native resolution of the external monitor; otherwise you'll still have distorted text on screen.
It's a bitch; see if there are any external solutions for your setup, like a video adapter through USB. Not highly performant and no gaming on them, but they can up the resolution quite a bit.