Passing data into a variable

Hi, 

All I want to do is pass numerical data into a variable, and then access it later. 

Specifically, I use the Read Vector Space Position VI to find the X and Y positions of my motors. When I press a button, I want the X and Y position at that moment to be saved, so that I can access this information later.

I would like to do this in a subVI.

I have read tutorials on functional global variables, but so far they have been quite confusing. Specifically I do not know how to place/use uninitialized shift registers. 

If someone could create a simple example code, that would be extremely helpful. I am using Labview 2011.

Thanks