What should I do to get rid of my feeling of joy and laughter at the mistakes of my brothers in reciting the Quran during prayer, and my fear of showing off (riya') and arrogance, especially if I become their imam?

One should praise Allah for the blessing of learning the Quran, memorizing it, and reciting it beautifully, and ask Him for steadfastness and sincerity. The way to show gratitude for this blessing is by not disparaging others and by striving to teach them. It is permissible for a woman to lead her sisters (in prayer) if they are females; indeed, it is not permissible for her to be led by one of them who does not recite Al-Fatihah well. However, if they are males, it is not permissible.