Hello, everyone!

I'm in the difficult position of being the new guy in the office and have been tasked with making new assemblies and models based on existing assemblies and models.  It's a mess, as it's clear there is a lot of legacy data that was either imported from elsewhere, or created by an untrained CAD operator.  As a result, I find myself often wanting to change the origin in an assembly or sub-assembly.  Can anyone point me in the right direction? 

YouTube is not helping.... 

As you can see in the attached, whomever made this one didn't use the origin at all. (that little blue dot is the origin)

Thank you for your time and assistance!