How can I change dateformat for auto-completition in Writer?

Dear Community Members,

I would like to change the dateformat shown on the sceenshot to a longer one, like “2019.januar.16” instead “2019-01-16”. How can I?

C:\fakepath\Screenshot_20190116_131542.png

Thanks in advance,
Julius

See Mike Kaganski’s answer at How do I change the default date/time format?.