Many "free download" sites advertising "Monotype Corsiva Bold" are actually offering the weight or non-authentic versions. Apple Support Community Legacy Systems:
He reached for his notebook on the desk to write himself a reminder for the morning. He popped the cap off his pen and began to write: Buy license tomorrow. Monotype Corsiva Bold Font Free Download
Use Alex Brush (available via the "More Fonts" menu) or Pacifico for a bold script look. Monotype Corsiva Bold Font Free Download