How to modify intellij new Project automatically provided .gitignore file

When I create a new Intellij project on my Mac it includes a default gitignore for me to use.  However, I want it to have more in it every time.  How can I change the default gitignore file?

It is handy to have the file automatically provided, but it does not include some files I walways want to be in the gitigore such as xm and iml

Thanks