Why does the data in "Walking" bear no resemblance to what I've done?
Sounds like you're confusing the Steps counter and a specific Walking activity. But I can't tell for sure with what you've posted so far.
Is the problem on the device? If so, you should post to the proper forum for that device.
If the problem is fine on your device but wrong on the app, then you'll need to tell us what device you're using.