This article suggests the most likely source for the quote commonly attributed to Socrates was actually crafted by a student, Kenneth John Freeman, for his Cambridge dissertation published in 1907.
Looking at the digital copy of the dissertation linked in the above article, it looks like the source for the Socrates quote is a combination of two sections of text on page 74 of the disertation.
Socrates quote from grandparent:
“Our youth now love luxury. They have bad manners, contempt for authority; they show disrespect for their elders and love chatter in place of exercise; they no longer rise when elders enter the room; they contradict their parents, chatter before company; gobble up their food and tyrannize their teachers.”
Quote noted as misattributed to Socrates and suggested as paraphrased from Aristophanes at end of wiki link from parent:
The children now love luxury; they have bad manners, contempt for authority; they show disrespect for elders and love chatter in place of exercise. Children are now tyrants, not the servants of their households. They no longer rise when elders enter the room. They contradict their parents, chatter before company, gobble up dainties at the table, cross their legs, and tyrannize their teachers.
Excerpt from Kenneth John Freeman's 1907 dissertation:
[Lines 5-7] "The counts of the indictment are luxury, bad manners, contempt for authority, disrespect to elders, and a love for chatter in place of exercise. [Lines 19-21] Children began to be the tyrants, not the slaves, of their households. They no longer rose from their seats when an elder entered the room; they contradicted their parents, chattered before company, gobbled up the dainties at table, and committed various offences against Hellenic tastes, such as crossing their legs. They tyrannised over the paidagogoi and schoolmasters."