I recently had a leak in my upstairs tub & did some research on mold before digging into my ceiling drywall in the office underneath.
Household bleach is no longer recommended for killing mold. A large % of household bleach is water. After the bleach kills surface mold, the water acts as yummy food to any mold under the surface & feeds it.

It's OK to use bleach on hard surfaces like countertops, but don't use bleach on porous materials like wood, which may have mold under the surface.
Use a thick paste mix of Borax & water to attack mold on drywall, wood, etc.
Do a search & some reading before continuing, & do be careful.
Thanks,
-Jason