In Windows, Double-click on the speaker icon in bottom-right corner of your screen (the area known as the "Systray") and make sure that the volume levels are all the way up. Your UA-1A has no external volume controls, but your volume settings can be set here.

In Mac OS (8 or 9), you can adjust UA-1A volume from the Control Strip, or from the Sound Control panel.

Did you try the "normalize" feature in your recording software? If you are unsure of how to do this, please contact the company who wrote your software for information.