@LoveMyDobe , Those marks look like plain ol water stains. I'd also say that if nothing has changed in four years that's good news. Must have been a lot of water coming in at the time if it leaked through all the joints.
Mold is a whole other issue. It essentially grows like a patch of weeds in cases I've seen. It starts in spots, usually where there is less air flow and high moisture. It slowly pops up new growth around the original location. I've also found that high moisture environments will start showing mold in multiple locations as time progresses.
I've dealt with the issue in places I've bought. In some cases it will scrub off. It's rare and usually is associated with dirty surface. That means scrubbing down the whole works before repainting.
Mold is rarely just the stuff you see on paint. When it's coming through the paint I tear out the rock and start over. High moisture destroys the paper and the gypsum becomes brittle. The framing underneath is often damaged as well.
There are shortcuts to remedy the issue. In most cases those solutions are short term unless the cause is addressed. Prolonged high humidity is a major cause.
