Not able to change the value for Last Modified attribute format

I am using Creo Parametric Release 4.0 and DatecodeM030

There is an attribute called Last Modified (PTC_WM_Modified_on ) for EPM object under the visualization and attribute group. I wanted to change the value for it.

PTC Suggested below articles and we followed it. But, those are not working as expected. We have documented each and everything.

https://www.ptc.com/en/support/article/cs49539
https://www.ptc.com/en/support/article/CS232016