date format settings not working

Options —> use custom date format problem: I was trying several combinations – d/m/y or d.m.y or dd.mm.yyy or dd/mm/YYYY and nothing works – no effect. I was trying to find solution here https://php.net/manual/en/function.date.php but there is no explanation about the syntax! So I don′t know which syntax i have to use. I need normal european date format like “day-month-year” Can you help me please?

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