Yippie for change and improvement!
If you are looking to filter out a non-running activity (say, walking a dog), you could classify it differently in the 'activity' field and those would show up differently. In the iPhone version, if I pick the 'me' category on the bottom left, I can see my stats, and there is a little drop down scroll to sort all activities vs. running vs. walking. I do not think you can retroactively change the categories, so you would need to just live with the irritation of it being less than accurate now and know it will be more useful as you collect more data.
If you are running/walking within the same activity, you can program your intervals in the workout screen and when you finish, you can view your pace per segment for that activity. I do not think it tracks changes between an interval activity- for example if you program that segment 1 is a 90 second interval in segment 2 is 0 seconds and you repeat it 12 times it will give you the pace for 24 segments but not compare all of the 90 second segments. Nor do I think you can easily compare yesterday's 90 second segments from today's.
Good Luck!