IBBQ-4T "change data source" function on graph page

Hi,
on manual I do not find the meaning of the key “change data source”. Can someone explain me the function of this key?

Greetings

Hello,
It is used to switch the data acquisition channel of the graph. For example, if the current graph cannot load data successfully for some reason, you can click “change data source” to switch.
When the chart data is displayed normally, you do not need to change the data source.