how to export printer settings from old computer to new computer?

The usual method is to install the printer driver software in the new computer first with default settings and then modify the settings.

You can take screen snapshots (Alt-PrintScreen) from the settings, and paste the snapshots, tab by tab, into a Word document if you want to document the settings.

If you happen to have a shared printer connected to the old computer, you can keep the old computer running while you install the printer driver software to the new computer through the network, remembering to assign a different name to the new computer. Now you can disconnect the old computer and change the name of the new computer to what the old computer was and join the domain, if your PC is a member of a domain. You can now connect the printer to the new PC and change the printer port in the Printer Properties from the network connection to LPT1: - if you use a parallel cable. The printer settings would have been transferred to the new PC and the other users should be able to print as before.

In a centrally managed shop the printer settings are usually pushed to the desktop from AD or NDS/Zenworks.

You could try the printmig.exe resource kit utility to migrate lots of printers:

http://www.microsoft.com/downloads/details.aspx?FamilyID=9b9f2925-cbc9-44da-b2c9-ffdbc46b0b17&displaylang=en