how can i upgrade macbook Air 13-inch,early 2014-10.9.5 [13f1911]

The highest upgrade for your Mac is Big Sur: macOS Big Sur is compatible with these computers – Apple Support (AU)

V-A-G-O Said:

“how can i upgrade MacBook Air 13-inch,early 2014 -10.9.5 [13f1911]”

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Upgrade to a New Mac:

Internal hardware is what it is. Your Mac’s hardware soldered into the LogicBoard to work as one complete device. So, next time you get a Mac, get one that suits your needs.

For Example, in Regards to Internal Storage:

Internal storage cannot be upgraded. It is what it is. So, the maximum internal storage capacity never increases, even if you upgraded your iCloud plan. Learn More here: What's the Difference Between Device Storage and iCloud Storage? Apple Support