Attachments opening in open office

My attachments are opening in open office even though the extension is docx how do I get them to open in word

You need to modify your default programme settings within the operating system.
Currently it is set to Open Office

Oh but everything else opens in Microsoft package and this is the first time its happened and it is a word doc I have never used open office. will look at it but I can see tells it to open in open office