Upgrade from MS Office 2019 32bit to 2021 64bit

Your pst files will remain in Outlook files folder and you can Import them into Outlook. I would make a backup of them anyway. It will be a new install, so yes, you'll have to go trough all the settings again.

Do you need 64bit? Any extremely large data to process?

Select between 32bit and 64bit Office

Important: If you install the 64-bit version, but want the 32-bit version instead, you must first uninstall the 64-bit version before installing the 32-bit version. The same is true if you installed the 32-bit version, but want to install the 64-bit version. See “Office (64-bit or 32-bit) couldn’t be installed” error.

26dipp said:

Thank you for the reply.
I just thought that I had been holding back with 32bit. The PC is a 64 bit system. I do not have to handle large files or large amount of data, so could stick with 32 bit.

Well, you have detailed explanation of difference in the link provided above.

I have switched to 64bit a decade or so ago. Not that I needed it for extra large files. Just something you choose with a new computer. And new install isn't so painful really. Your decision.

26dipp said:

I wanted to install Office 2021 64 over an installed 2019 32 bit version. I have always used 32bit because of come compatibility issues with other devices. This is not necessary anymore. So I wanted to go to 64.
In the past the 32bit versions simply installed over each other, but the 2021 Office said I had to uninstall the older Office first.

The need to uninstall the previous version is caused by your desire to use 64 bit Office now.
If you had chosen to continue using 32 bit Office then you would not have needed to uninstall the previous version.
If you just go ahead with the installation without uninstalling the previous version then Office 2021 will be installed in its 32 bit variant.

26dipp said:

Will I loose any of my files like the PST files and other settings, i.e. do I have to change all my old settings again?

If your Outlook datafile is in its default location then it might be overwritten with an empty copy. That always used to be the case but I can't check for you because I always move my pst files to other locations so they are within the folders I routinely back up.
Other Outlook settings will also be overwritten so are worth backing up beforehand - see Find and transfer Outlook data files from one computer to another - MSSupport


Best of luck,
Denis