What this video covers
Mold cleaned off a surface that returns within a fortnight is not a cleaning failure. It is a diagnosis failure.
The clip makes the distinction plainly: what you removed was the visible colony, which is the symptom. The moisture feeding it is still there, so the surface is damp again within days and growth restarts from spores that were never going to leave.
The takeaway
If it came back, stop buying stronger cleaners. Find the water. A leak, a cold surface collecting condensation or humidity that never drops is the actual problem, and until it is fixed every clean is temporary.
Read the full written guide: Mold Remediation: Fixing the Source.