The Unwanted Clock Sync
By default, macOS continuously pings Apple’s official Network Time Protocol (NTP) servers (like time.apple.com) to ensure your Mac’s clock is perfectly accurate down to the millisecond. For 99% of users, this is exactly what you want. However, there are specific, niche scenarios where automatic time syncing is a massive annoyance. For instance, if you are a software developer testing how an application behaves when a free trial expires, you need to manually “fast forward” the system clock. Or, if you are playing an offline video game that uses real-world time to gate progress, you might want to change the date to skip a waiting period. If you try to change the time manually while auto-sync is enabled, macOS will simply instantly overwrite your manual change with the real-world time the moment it reconnects to the internet.
How to Disable Network Time Sync in System Settings
To take full manual control of your Mac’s clock, you must severe its connection to Apple’s time servers.
1. Click the Apple logo () in the top-left corner of your screen.
2. Select System Settings (or System Preferences on older versions of macOS).
3. In the left-hand sidebar, click on General.
4. In the main pane, click on Date & Time.
5. Look for the toggle switch labelled Set time and date automatically.
6. Click the switch to turn it Off. You will likely be prompted to enter your Mac’s administrator password (or use Touch ID) to authorize this core system change.
7. Once the toggle is off, the greyed-out “Date” and “Time” fields below it will become editable.
8. Click the Set… button next to the Date and Time fields to manually input whatever year, month, day, and time you desire.
Important Warnings About Manual System Time
While changing the time is useful for testing, you must remember to turn Set time and date automatically back on as soon as you are finished. Running a computer with a wildly incorrect system clock will cause severe problems with internet security protocols.
Specifically, if your Mac thinks the year is 2015, but you try to load a modern HTTPS website whose security certificate was issued in 2023, your browser will block the website and display a massive “Your connection is not private” or “Certificate expired” error. Furthermore, services like Apple iMessage, iCloud sync, and software update downloads will completely fail to connect until your clock is accurate again.