Openfire 3.81 - Java Memory

How would I go about increasing the java memory?  I read a few articles out there but they refer to Linux or running Openfire as an application and not a service:

I have Openfire 3.81 running on Windows 2008 R2 Server, using Openfire service

I already have this setting in place:

Would like to increase from the 256mb to 512mb.

Exact steps would be so helpful

Thanks for your time!