How to Caption A Chart Axis

[#1]

In the image above, I would like to change the text of the graph to simply read "Post Date" rather than the date format string.  How do I do that?  I searched all over the property box for the chart, but could not find the right setting.

[SunilChauhan · Accepted solution]

There is label text box below this expression

you can rename from there.

see the attched image for reference.

[#3]

Thanks; the button looked greyed out at first.