As the topic says, is there any way to make other parts of the world use the same type of atc used in Europe i.e  QNH in Hpa instead of inHg. Because as far as i know only the US uses that?

You might be looking for this version of VoxATC for the UK and Europe:

 

http://www.rcsimulations.co.uk/shop/page/9?sessid=XINLoYVZvSKXig5oItigzQAT8Mkfyb9OtwC4nGBfDIaMCkUdIfr6gIpDOeeUaB7s&shop_param=

 

Unfortunately it's only available as a boxed copy and costs more.

Aah :(  oh well thank you for the info