Additional settings-related features and issues within Microsoft Teams for business
Hello, Spurný
I am Igor and I will be glad to help you with this question :)
You have two differente settings under teams settings
App language and Keyboard language
App language determines the date and time format.
Keyboard language overrides keyboard shortcuts.
At this moment, there is no different way to change the date/format without changing the app language. Teams should respect your date/time format from the Windows settings.
Open Windows Settings.
Click on Time & language.
Click on Date & time.
Choose the date;time format