Current flows in loops (always) and your power supply actually has two loops that matter for this.
Simplifying slightly there is a primary side loop, Live -> Psu -> Neutral (completed by the power companies equipment), and a secondary side loop made up of the 12V wiring, the 12V return and the load.
In both loops the same amount of charge flows into and out of the PSU on its respective loop, so on the DC side it is 41 coulombs/second (at full load), and on the AC side it is an average of around 4 coulombs/second (Actually closer to 5 or 6 probably for various reasons, also on the ac side this is slightly simplified).
In both loops the same amount of charge exits the supply on one wire as enters it on the other, energy is converted by moving the charge thru a potential difference and it is energy that is transferred between the primary and secondary circuits, not charge.
Note that because the same amount of charge exits on one wire of the loop as enters on the other (to a very good approximation), there is little net charge built up in the power supply, it this condition did not hold the charge on the supply would build until something (quickly, and probably explosively) failed.