US Immigration from United Kingdom

Hi everyone, just a quick silly question haha

So I grew up in Kosovo and moved to the United Kingdom when I was 7 years old, and then became a British Citizen. I travelled to Australia for about 10 months in 2013 then came back to the UK as this is where I live.

Do I need a police report for Kosovo, Australia and the UK? Or just the UK?

This is very confusing so if anyone can shed some light it would be awesome!!