Adam - I'm not too clear on the exact problem here. Are you saying the meter goes to 0db immediately when you arm the track WITHOUT any input. If so, then obviously it is going to clip when you start singing or playing anything.
When you arm a track without any input, the meter should be showing a signal equivalent to your noise floor. Depending on the quality of your equipment, this should be somewhere around -50 to -90 db (the lower the better). When you give it input, it should show you the signal strength. You want to adjust your input so the loudest passages peak in the -3db range.
Then again, perhaps you already know all of this and somehow just changed your record meter options to show an RMS signal rather than a Peak signal.
If so, look for Icon on the toolbar just above your Tracks which looks like a couple of pencils (I think they are actually supposed to be meters). It should be the furthest one to the right. Next to it you will see a drop-down arrow. Select the arrow and you'll get a choice for "record meter options" where you can select what the meters display.