You should keep that open

I was revising a design from another worker.

Boss: Can you change the color of the button on this like the previous design?

Me: Sure.

I pull up the previous design X.

Boss: NO not this one, the PREVIOUS ONE!

I pull up another design guessing at which "previous" one she is referring to. I open up design Y.

Boss: YES this one!

5 Minutes later...

Boss: Can you pull up the previous design again?

I pull up the design from project Y.

Boss: NO not this one!

I pull up the design from project X.

Boss YES this one, you should always keep it open!