Reselecting which player or permanent a creature is attacking doesn't cause "whenever this creature attacks" abilities to trigger.
Misleading Signpost
You may cast Misleading Signpost outside of a declare attackers step. If Misleading Signpost enters the battlefield outside of a declare attackers step, its ability simply doesn't trigger.
If an ability targets something controlled by the "defending player" of an attacking creature and the defending player for that creature changes before that ability resolves, the ability won't resolve because its target has become illegal.
Magic: The Gathering · ™ & © Wizards of the Coast · Illus. Julian Kok Joon Wen
Card data via Scryfall. Rarix is fan-made; not endorsed by the rights holders.
