How to I change the default date format from DD/MM/YY to DD/MM/YYYY

[FairKing]

How to change the default date format? It is very annoying in every document, and even in every cell and everywhere it comes out with YY. And even if I change the cells date format (docx or xlsx) next time after I open and change anything it resets back to YY.

Same with numbers. I try to change everywhere to 0.00 but magically it resets me back to 0.##.

I searched all the settings including Tools - Options - Languages and Locales. Nothing there.

Please help. Thanks.

[FairKing]

Also, with Formula, I am not able to change the format completely.

Please find attached document as an example how do I make it 28.20 (instead of 28.2)???

test.zip (4.9 KB)

[koyotak]

… by conditional formatting automatically displays a date value (!) as selected. The datum format must first be set as a template.
LO-CALC_Datum conditional formatting_083748.ods (149.7 KB)