In Settings > Appearance > “Use system time format” does not change many (any?) things where the date appears.
It currently shows as DD-MM-YYYY format. There’s no options to configure for other formats, including the International Standard - ISO-8601 (Wikipedia article) - which shows dates as YYYY-MM-DD.
@Tarun - This setting is only meant to change the time format, not the date. If using both the system date and time format is something you’re looking for, I can let the team know for future consideration.
@Tarun - My Windows settings are UK i.e. DD-MM-YYYY and yet my GlassWire shows as MM-DD-YYYY! Where does that come from? I would prefer it to be UK format.