It looks like RH doesn't change title of graph when Zoom have
These both values are independent. You can scroll temperature back in 15 Minutes to see the rest of the past 60 minutes. So zoom factor does not change viewable time span just the time you see at once.
i see. so RH just remembers last 60 min and when i select 15 zoom I can slide left and right.
mm. may be this static label makes a user is a bit confused. the label somehow should hint a current zoom level
After the first hour there are per hour curves as well and these would change the label.
You see the zoom level at the time scale already. Did not want to add too much labels all around.