If the Windows clock is exactly an hour or several hours wrong, inspect the time zone and daylight-saving settings before manually adding or subtracting hours. A clock that looks correct after a manual adjustment can still be configured for the wrong region.

Compare the date and time with a trusted independent device. Note whether the difference is a fixed number of hours, an incorrect date or gradual drift. Also record whether it began after travel, a reinstall or a period with the computer powered off.

Separate time from time zone

Open Settings, Time & language, Date & time. Set time automatically controls the clock's time setting. Set time zone automatically controls which regional zone is applied. They are different options.

If automatic zone selection gives the wrong result or you prefer a fixed location, turn that zone option off and choose the correct named time zone from the list. Check the relevant daylight-saving control as well. Microsoft explains that automatic zone selection handles daylight-saving automatically; a manually selected zone has its own adjustment option where applicable.

Use the zone intended for your location rather than copying a fixed UTC offset from an old note. Offsets can change seasonally. On a managed work computer, let IT handle controls that are restricted or configured by policy.

Observe whether the correction persists

Check the displayed date and time after the change, then again after a normal restart. Review a calendar appointment with a known time, remembering that an application or online account can have its own display-zone setting.

If the clock repeatedly loses the date after power is removed, preserve that pattern for diagnosis. Repeated manual corrections can hide useful evidence, and the issue may extend beyond Windows' time-zone selection.

If a website or application still reports a security or connection error once time is correct, investigate the remaining error. Do not bypass certificate warnings merely to compensate for a clock problem. The successful result is a correct, persistent time configuration, not simply making one warning disappear.

Reference: Microsoft Support.