Press and hold (or right-click) the MP4 file you want to play, select Open with, and then choose your preferred file player from the list of applications.

Download and install Skype for Business on your PC. Sign in to and out of Skype for Business. Set up an audio device for Skype for Business. Set up and troubleshoot Skype for Business video

如果应用已打开，请在任务栏上找到应用的图标按钮，长按此按钮，然后向上滑动，直到出现“应用列表”。 如果你使用的是鼠标，请在任务栏上找到应用图标按钮，右键单击此按钮，然后选择“固定到任务栏”。

Important: If your device is out of support, it is no longer receiving security updates from Microsoft and may become more vulnerable to security risks and viruses.Therefore, we strongly recommend that you update to the latest version of Windows. Each version of Windows is supported for 18 months.

Test your camera with the Camera app. Select Start , then choose Camera from your apps. If you're asked to allow access to the Camera, select Yes.If the camera works in the Camera app, the problem might be with the app you're trying to use.

Learn how to download, install, and configure Language Accessory Packs for Microsoft 365 for additional display, help, and proofing tools.

Training: Microsoft OneDrive lets you store your personal photos, files, and folders in one place, and get to them anytime, anywhere. Learn more in this online training video.

Explore OneDrive support, help, and learning resources. Learn how to protect your important files, documents, and memories with OneDrive.

Alternatively, you can install any website by going to the top corner of the browser and select Settings and more … > Apps > Install this site as an app.

Tip: If you're a Microsoft 365 Family or Personal subscriber you get Microsoft Defender, our advanced security software for Windows, Mac, iOS, and Android, as part of your subscription.Learn more at Getting started with Microsoft Defender.