Symptoms
- Second monitor shows the exact same thing as the first
- Can't drag windows onto the second monitor
- Mouse cursor doesn't move onto the second screen
- Presentation or second screen shows the wrong content
Likely causes
- CommonDisplay mode set to 'Duplicate' when 'Extend' was wantedDuplicate mirrors the same image, which looks like the second monitor isn't doing anything different.
- CommonDisplay mode set to 'Extend' when 'Duplicate' or a single display was wanted (e.g. for a presentation)Extending can confuse presentations, showing different content than intended on a projector.
- PossibleMonitor arrangement in settings not matching physical desk layoutEven in Extend mode, the cursor can behave oddly if the virtual arrangement doesn't match reality.
What to do
- On Windows, press Windows key + P to bring up the quick display mode menu (PC screen only, Duplicate, Extend, Second screen only) and pick the one you need.
- On Mac, go to System Settings > Displays, and either check or uncheck 'Mirror Displays' depending on whether you want duplicate or extended mode.
- For extended mode, open Display Settings and drag the monitor icons to match your physical desk arrangement so cursor movement feels natural.
- For presentations, use Duplicate or 'Second screen only' mode so what you see matches what the audience sees.
- If windows won't drag onto the second monitor, confirm you're in Extend mode, not Duplicate, first.
- Restart the presentation app after switching display modes, since some apps cache the display configuration at launch.
Tools and parts
- None
When to call a pro
This is purely a settings choice, not a fault; no professional help is needed, just picking the display mode that matches what you're trying to do.
Safety
Generally low risk
Generally low risk for a careful person. Stop if anything looks different from what this guide describes.