Many older people disapprove of how young people do things.
Tips
grammar
看不惯 is a resultative complement structure: 看 (see) + 不 (not) + 惯 (accustomed). The positive form is 看得惯 (can get used to seeing). This pattern works with other verbs too: 吃不惯 (can't get used to eating), 住不惯 (can't get used to living somewhere).