Is it better to continue to remain silent and endure the scolding of one's parents for not praying the supererogatory prayers in front of them, or to clarify the matter to them for fear of showing off, knowing that they will be pleased by that?

Concealing an act of worship is better, unless its open performance leads to a preponderant benefit, such as being emulated by someone who gives charity. Performing supererogatory prayers at home is better, as it is closer to sincerity and further from showing off. Informing one's parents about your acts of worship is better if it dispels ill-conceived notions or brings joy to them, while striving to achieve sincerity.