What is the best domain for global ranking?

Hello all. I recently starting posting blogs to moonsand.co and I have noticed these very quickly ranked in the US, however only very few of the keywords ranked in countries such as UK, Europe, Australia, New Zealand etc. My current domain is .co but I was wondering if this is maybe the reason it is mainly ranking in the US?

I would like my website to rank for the keywords in all English speaking countries. Is there something I am missing? or maybe a tip or trick I need to use?

Any help greatly appreciated here!