Any way to keep the TiVo Premiere on a particular tuner?

The TiVo premiere has two tuners. When you are on a certain one (not sure whether its 1 or 2), you can flip between channels using the ENTER/LAST button on the remote, and both retain the last 30 minutes of the program. Hence, I can pause one, flip to the other one, and when there's a commercial flip back to the paused show and watch it. When you are on the other tuner, this does not work; it clears the data as soon as you change. The problem is I never know which tuner I am on, and it seems to change randomly. It will work, then an hour later or so I'm on the other tuner to no doing of my own. I'm not sure I can explain this any more clearly, but if you've run across this then you know exactly what I'm saying. My question is, how to know which tuner I am on. Perhaps a code to enter? Thanks.