Support and resistance as prior trade

Why does this course build a zone from closes rather than from the highest and lowest wicks?

• Wicks are not shown on most crypto charts
• Closes are where each period settled; a wick is a few trades at an extreme
• Closes are always round numbers

Price closed below a support zone, then rallied back into it and turned down again. What is that called?

• A failed zone that should be deleted
• A role flip: the old support acted as resistance on the retest
• A new range, because price is back inside