Good to see you found your answer, have only just seen your question (not all of us can spend all day logged on here

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The set all time record is for if you have something that is abnormally high or low you can either fill in what you know is correct, or just do as you did to get a new result to set itself.
Can also be used as I did to set an all time record that occurred in your area before the station was set up.