Edit Field Buttons on a Pivot Chart

On the pivot chart layout tools Tab, under "current selection", I can select the chart element I wish to edit (a chart button). When I try to format the selection the edit box opens, but it will not let me enter any changes. I can also "right click" on the button, but only chart editing selections are listed. Any ideas? I created a pivot chart and the button labels are truncated, and i have no way to make the button larger, or decrease the size of the text.

Have you tried editing the field names in the source pivot table?

As it turns out, the problem is the computer I was using had its graphics set as HD graphics with larger size fonts. This truncated all the buttons.

But how did you solve the issue, I am also facing similar problem "button labels are truncated"