First, search the help docs and this forum. Maybe your question has been answered! The debugging steps can help, too. Still stuck? Delete this line and proceed.
What I’m trying to do
certain markdown formatting does not change the text; for instance, **testtest** will not be bold, but *test* will be italic;
Go to Settings–>Appearance–>Text font and set your font to Courier New. You should now distinguish bold text. You can also use light mode by opening command palette and running command Use light mode. In light mode bold text is easier to recognize.