upgrade my Mac from 32 bit to 64 bit?

giancarlogcdigiphoto wrote:

Can I upgrade my Macbook Pro from 32 bit to 64 bit?

Regarding the pop-up—this is a generic warning only. You have to do nothing, 32-bit apps continue to work on both High Sierra & Mojave.

In the future release of macOS 10.15 Catalina, applications will have to be 64-bit. App developers will issue updated apps if they want their apps to work on these future releases. Catalina will only run 64-bit apps only.

32-bit app compatibility with macOS High Sierra 10.13 ... - Apple Support

https://support.apple.com/en-us/HT208436

As Bob says, Macs have been 64-bit for a long time so have all Apple default apps. Starting with Catalina any third party apps that may be 32-bit will need to be upgraded before they will run. For those you should check with their developer for an upgrade. Of course, if you do not upgrade to Catalina they will continue to work.

Mac computers have been 64 bit for over a decade. What is it you really want to do?