أحسن الله إليكم what is your advice for the one who struggles to correct people when they error in front of him?

Shyness that stops you from saying the truth is not praiseworthy shyness. Correct gently, with kind words, the way you would accept it for yourself, and if the moment is not right, remind the person later in private. However if the evil will outweigh the good, then do not advise.