I have an old MacBook, needs updating but need to know how to update, please assist. My current MacBook is Sierra MacOS 10.3

"I have an old MacBook, needs updating but need to know how to update, please assist. My current MacBook is Sierra MacOS 10.3"

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For reference....

Updating the macOS:

Determining which Update(s) will Install:

I. Verify Compatibility:

A. Start Here: Learn About Compatibility and how to Identify your Specific Mac Model - Apple Support

B. How to Verify:

I. Reveal your Model:

What is the Model of your Mac? To find out...

1. Go to: Apple menu
2. Click: About this Mac
3. View: Second Line-Down

then...

II. Compare the Results:

See if the Model you found is shown here:

• macOS Sonoma is Compatible with these Computers - Apple Support
• macOS Ventura is Compatible with these Computers - Apple Support
• macOS Monterey is Compatible with these Computers - Apple Support
• macOS Big Sur 11 Hardware Requirements - Apple Support
• macOS Catalina 10.15 - Hardware Requirements - Apple Support
• macOS Mojave 10.14 - Hardware Requirements - Apple Support
• macOS High Sierra 10.13 - Hardware Requirements - Apple Support
• macOS Sierra 10.12 - Hardware Requirements - Apple Support
• OS X El Capitan 10.11 - Hardware Requirements - Apple Support
• OS X Yosemite 10.10 - Hardware Requirements - Apple Support

III. If Compatible:

Back Up your Mac First:  Be certain you Create a Time Machine Backup of your Mac, so that way you can have something to restore your Mac from, should anything go wrong with the reconfiguration.

Hi,

It depends on how old your MacBook is. You can see the model of your MacBook at Apple Menu > About This Mac...

If System Preferences > Software Update says nothing about upgrade, you can't upgrade your MacBook, though I assume you could upgrade till High Sierra which is available at following site.

How to download and install macOS - Apple Support