How do I get words Bold within a text message while using iMessage?

• I have in iPhone 7 Plus. After selecting the text I want to revise, I tap to get the B/I/U: Format selection. I choose B (for Bold). Then an * is put on each side of the word or words I want in Bold (*Bold These Words*). Then I send my message by iMessage or WhatsApp.
• The word or words that are within the asterisk ARE NOT BOLD. The message is just delivered with the asterisk around the word or words. (*Bold These Words*) It should be Bold These Words
• How do I get a word or words Bold within a text message while using iMessage or WhatsApp?
• I have done the following steps. It does not work. Does anyone have a solution? Or does this feature not work?

Select and edit text

1. To select text, do any of the following:

• • Select a word: Double-tap with one finger.
  • Select a paragraph: Triple-tap with one finger.
  • Select a block of text: Double-tap and hold the first word in the block, then drag to the last word.

1. After selecting the text you want to revise, you can type, or tap the selection to see editing options:

• • Cut: Tap Cut or pinch closed with three fingers two times.
  • Copy: Tap Copy or pinch closed with three fingers.
  • Paste: Tap Paste or pinch open with three fingers.
  • Replace: View suggested replacement text, or have Siri suggest alternative text.
  • B/I/U: Format the selected text.

[Email Edited by Moderator]