upgrade my os macbook?

Hi @azumi272

You are probably looking in the app store app and can't find it.

Apple Catalina can be downloaded here

If you mean the new OS, Big Sur follow the below instructions.

1. System preferences can be located by clicking the apple logo in the top left of your screen/menu
2. When you click on the "Software update" icon within the menu, the next steps should be very straight forward.

As their profile says they are on OS X 10.10 (Yosemite)

System Preferences> Software Update does not exist in Yosemite

that option only came in with macOS Mojave 10.14.

Prior to that updates were handled through the App Store Updates page.

Which OS you can upgrade to will be governed by which model and year your mac is.

Click on the  top left of your screen click on About This Mac to find out the year of your mac.

For macOS Catalina,

Open Safari and click on this link, 

How to get old versions of macOS – Apple Support

Go to Check Compatibility to see if your mac qualifies for the OS upgrade you want.

Then go to the Download OS section and click on macOS Catalina.

If you want to or are able to install Big Sur, open Safari and click on the link below.

How to upgrade to macOS Big Sur - Apple Support

Before upgrading make a full back up of your Mac.

Check that third party apps you use have updates available for the new OS.

https://roaringapps.com

Check that your printers/ scanners etc have updated drivers and software available for the new OS.

Connect your mac to your router via cable rather than rely on WiFi.

Do not use your mac while it is downloading

and do not use any other devices that share the same internet connection.

If the App Store says ‘Open’ then it is detecting a previous download of the install app

go to the Applications folder locate Install macOS ******.app.

Move it to the Trash, empty the Trash.

Restart, click on the link again, the App Store should say ‘Get' or 'Download'.

If you are considering upgrading to Catalina or Big Sur be warned they do not support 32bit apps.

Your Mac is probably running 32bit apps and these will need to be updated to 64bit apps,

some updates may be free, some may be paid. Use this app to discover which apps you have

are 32bit, https://www.stclairsoft.com/Go64/ then contact the developers of the software to see

if they are providing 64bit updates or alternatives.