I want to reinstall big sur and not Monterey , presently I have El Capitan. Please help.

Hi,

Go to the Apple Menu > About This Mac to see exactly which Mac you have, then find out if it is compatible with Big Sur here:  How to get old versions of macOS - Apple Support. Use the same link to download it.

Before upgrading, backup, check apps and peripherals for compatibility with Big Sur.

Big Sur will not run 32 bit apps, so download Go64 and scan your Mac to see which of your apps are 32 bit and will need to be upgraded/replaced: https://www.stclairsoft.com/Go64/

Some apps may be 64 bit but still not run on Big Sur; you can check them out here: https://roaringapps.com/apps

If the User ( you ) used the supplied link from previous posting by @ tjk >> Safari will open a redirect and open the Apple Store where the download can commence. of Big Sur.

It would place a New Application on the Applications folder of this computer.

The New Application would be called " Install Big Sur " Does it appear in the mentioned location ?

Going to " go to system upgrade the system is giving me the option to upgrade to Monterey " is not the place to commence the Installation of Big Sur but may offer the Monterey installation

It occurs to me and maybe the previous Contributor - this computer would have to be running macOS 10.14 Mojave or higher to get the " go to system upgrade the system " as that specific Apple Feature was only Introduced in Mojave and above and not in El Capitan.

Hmmm, it should have opened when it finished downloading. Try double clicking on the installer.