How to add the timestamp on the Power BI Line Chart Graph

I have worked with Line Graph reports, and the boss is happy with my works, however, he wanted to have the timestamp on the line graph that when he printed the line graph report, he wanted to see the timestamp.    I am able to get around with it by adding the card to the top of line graph with time value.  Actually, they are separated object.  So when I tried to expand the line graph, the time stamp is not showing. My question is how I make the timestamp as the part of line graph that when I expand it or print it.

Thank you....

GW