What should I do if the Microsoft Edge homepage has been changed to 360?

The immediate priority is to remove the 360 homepage hijack and restore your browser settings, as this change is almost certainly the result of unwanted software, often bundled with other downloads. This alteration is not a benign preference switch but a common symptom of adware or a potentially unwanted program (PUP) that has modified Edge's policies or shortcuts. Your response should be systematic, beginning within the browser itself before escalating to more comprehensive system checks.

First, attempt to rectify the issue directly through Microsoft Edge's settings. Navigate to `Settings` > `Start, home, and new tabs`. Under the "Home page" section, ensure the toggle is set to "A specific page or pages" and replace the 360 URL with your preferred homepage, such as `edge://newtab` or a custom site. Simultaneously, check the "New tab page" setting to ensure it hasn't been similarly compromised. Crucially, examine your browser extensions by going to `edge://extensions/` and remove any unfamiliar or suspicious add-ons, especially those you do not recall installing. It is also prudent to inspect Edge's shortcuts on your desktop or taskbar; right-click, select `Properties`, and examine the `Target` field to ensure no rogue URL (like the 360 address) has been appended after the `msedge.exe` path.

If the homepage reverts to 360 after these steps, the infection is likely being enforced at a deeper level by system software. Proceed to scan your computer with reputable security tools. Run a full scan using Microsoft Defender, which is built into Windows, and supplement this with a dedicated scan using Malwarebytes, which is particularly effective at detecting and removing adware and PUPs. During this process, review your system's installed programs list in the Control Panel or Settings, sorting by installation date to identify any recent, unfamiliar software that may have been installed alongside a legitimate program and uninstall it.

Should the problem persist even after scans and cleanups, the hijacker may have employed group policy or registry edits to lock the setting, a more advanced form of browser manipulation. In this case, you can search for "Group Policy Editor" (`gpedit.msc`) if you are using Windows Pro or Enterprise, and navigate to Computer Configuration > Administrative Templates > Microsoft Edge to check for enforced policies. For most users, however, a reset of Microsoft Edge is the most definitive solution. This can be done within `Settings` > `Reset settings`, choosing "Restore settings to their default values." This will clear all temporary data, disable extensions, and revert homepage and search engine settings, which should eliminate the hijack. As a final preventative measure, be meticulous about download sources, always selecting custom/advanced installation to decline additional bundled software, and maintain updated security software to block such intrusions.