In the Visual Studio Designer, when you open the MainForm and click the ChartByArray control then look in the Properties window on the right (just like the attached picture shows).
That is where you follow the flow of ChartAreas - Axes - X Axis - Label Style - Format (or eventually make changes to Series or Legends or ...).
Whatever control you might be using on the form, you should familiarize yourself with that control's properties which are shown in the "Properties" window.
By changing the properties you would be manipulating the control's appearance / behavior.
This ChartByArray control is not designed in the same way as ChartBySampling control, so suggested actions should not be sufficient to make it show the current time on the X axis.
You can try replacing the stock ChartByArray control with the attached one to see if that comes any closer to what you want to have displayed.
Refreshing of the chart can be done by using one of the following approaches:
** with the PLC, by assigning an address to the PLCAddressRefreshAllPoints property
** with additional code, which would manipulate the RefreshAllPoints property, provided no address was entered in the PLCAddressRefreshAllPoints property
** automate the refresh by un-commenting the code inside the Region "Subscribing and PLC data receiving", as marked, provided no address was entered in the PLCAddressRefreshAllPoints property. The PollRateOverride of the driver itself could be set to 1000 for this automated example.