Please explain to me how D=A-D is supposed to flow

[eVh1955]

Hi.  I'm confused why the address can't be 11111, as highlighted in yellow



But still has to be 23456.  



If these images are hard to see please let me know.  Thanks.

[WBahn]

The only time the A-register (which IS the address register) can change is either when an A-type instruction is executed OR the dest=A bit is set in a C-type instruction.