If you see the same thing on both displays, you should start by making sure the displays are Extended instead of Mirroring ...

Duet Display lets you use any Android device as a second screen for your Mac, whether wired or wireless, giving you extra space for multitasking.

Sidecar in macOS turns your iPad into a second display, but it's limited to certain Macs and iPads. Thankfully, a few ...

Choose Mirroring or Extended Display: Mirroring: Duplicates your Mac’s screen onto your iPad. Extended Display: Treats your iPad as a separate monitor, expanding your workspace. Customizing Your ...

The Extend Mode, as its name implies, lets you turn your second device into an extended desktop for your PC. This comes in handy when you want to increase your overall screen workspace.

A dual-monitor set-up can help to increase productivity, but what if your second screen isn't being detected? Here's what to try to fix the problem.