While you're diving, those two bits of information are calculated, and while I'm not familiar with this computer, here is my understanding of the factory setting: You may set either of these attributes to alarm, so those factory settings probably relate to when the alarm will sound. The manufacturer has decided that the elapsed time alarm could be bothersome to divers who are, for example, on a guided dive following the guide's dive plan -- so the decision was made to factory set that feature so it wouldn't sound unless the user needs it to. Dive time remaining is set very low -- again, so the alarm doesn't sound for most people on most of their dives. You can reset them both as you want.
