If you are using Internet Explorer and you would like to retain your password for the duration of your search session you need to make sure that your browser settings are set to "always allow session cookies". Go to Tools / Internet options / Privacy / Advanced / Select "Override Automatic Cookie Handling" and then select "Always allow session cookies", then click OK / OK.

You should only need to type in the password once per session for each of the "Quick" or "Advanced" query screens.