Hello there, how can I update my mac

Did you already try to search for an update in the macOS AppStore?

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If you don't see Software Update

If you don't see an item named Software Update, choose View > Software Update from the menu bar in System Settings or System Preferences. Or use Search in the corner of the window to search for Software Update.

If your older Mac doesn't include Software Update, open the App Store app instead. It's in your Applications folder. Then click the Updates tab in the App Store to check for updates. You can also search for software by name.

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copied from: Update macOS on Mac - Apple Support

Which Mac model do you have?

If your Mac meets the hardware requirements, follow the steps mentioned in this article, after you opened it in Safari:

How to get old versions of macOS - Apple Support

eshete48 wrote:

MacBook Air (13-inch, Early 2015)

Your Mac can be upgraded to macOS Monterey 12.6.3. Since you are still running Yosemite you may have to upgrade to El Capitan first.

You can get both from the link that was posted.

How to download macOS - Apple Support

Which Mac, model and year do you have? If you aren't sure, check under the Apple menu > About This Mac.

Did you try to use Recovery Mode to get the macOS update installed automatically?

Check this article for the needs steps:

How to reinstall macOS - Apple Support

Get an external drive to install to, so we stand less chance of losing anything.

OS X Yosemite is the operating system. Which Mac; iMac, MacBook Pro, etc., and what year?