upgrade to a 64 bit .

BobMarley62 wrote:

Hello I would like to upgrade to a 64 bit . How can I do so ?

There is a generic warning pop-up.

You have to do nothing, 32-bit apps continue to work on both High Sierra & Mojave.

With the 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 this newest macOS upgrade

This may require you to download updated versions of your old apps if they no longer work when you upgrade to Catalina. In the case of all third party app—visit the associated webpages for your updates.

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

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

Macs are already 64bit. If you mean upgrade 32bit apps to 64bit, contact the developers.