I'm late to the party I know but I'm a retired programmer and I plan to catch up quickly. I've used Scratch to teach Hour of Code and I'm basically familiar with it.But my project is currently exhibiting strange behavior with respect to the initial mouse event, which is playing a sound I don't think should be playing at that point. I've shared the project at (I think; new at this) https://scratch.mit.edu/projects/115896755/
I was unable to duplicate the behavior you described, because your project did not play any sounds for me at first.
After clicking around for a while, I eventually got the scripts for the
house sprites to behave correctly.
There is an obvious error with the script for
Scratch can be difficult to debug, but don't beat yourself up too much about Pset 0. You should be much happier once you start working with C.