Welcome to YorkieTalk.
Congratulations on your new pup.
In the morning when Brando poops on the pad, praise him profusely for his accomplishment and give him a small treat (I use kibble to train), "Good boy Brando! Good poopies on the pad!" Then show him how you dispose of the poop right away. My boys seem to appreciate that part of the process, probably because dogs do not like their living areas soiled, especially with poop.
The second part, pooping behind the toilet when he is home alone, that will likely improve with age when Brando is able to better control when he does his business. He will probably wait until you are home from work to poop. For now, you could try having him watch you move the poop to the pad and tell him, "poop here, on the pad," and then dispose of it.
Giving him positive reinforcement and instruction should help improve his habits.
I hope this helps.