Sometimes you want custom label on x-axis. You can this with a little workaround described below.

Add Vertical line

Go to Chart annotations > Annotations and add vertical line anywhere on the chart.

Modify the line

Click on this line and:

1. Set Position (for Time chart - date, for Category chart - #0, #1, #2 etc.).
2.  Check Line > Between observations.
3. Select Content > Axis value label: 'Show'.
4. Check Custom style, go to Appearance > Color > […] and change 'Opacity %' to 0.

Modify label

Click on new label on chart and:

1. Check Custom style, under Appearance > Orientation please select 'Horizontal'.
2. Under Border > Border width please select 'None'.
3. Apply other graphical changes if needed.

Paste in text

Double-click on label and type in new number, date or use Dynamic text.