Why do you have credit card debt at all? That’s why they think you are making less.
You get a higher credit limit if they think your income is higher.
Also, parent poster is likely paying interest, which is the worst thing you can do on a credit card.
It improves your score, for sure. Your credit score is an assessment of your value as a customer. A customer who pays off their balance every month before incurring any interest is lower value than a customer who runs a balance and makes payments. The bank wants more people like that.
What impacts your score (in this axis) is utilization of revolving credit: credit used over credit available. Driving the numerator to zero will increase your credit score. Increasing the denominator will also increase your credit score. There is no situation where—all else being equal—increasing the numerator will increase your credit score.
> Your credit score is an assessment of your value as a customer.
No, your credit score is an assessment of your trustworthiness to a creditor, and the expectation that you will pay off any balances in full. Individuals with high credit scores are not generally directly valuable customers as they carry little revolving debt and are given low interest rates for mortgages and car loans. They accrue and use significant amounts of credit card rewards, which further cut into your profits. However, they (generally) make more and larger purchases so you make more money on merchant fees than you do with other cohorts.
This is absolutely never true.
Paying off a card every month is not "carrying a balance". Not paying off a card every month results in paying 15%+ rates in interest on the balance carried and actively lowers your credit score as long as you do it.
If you are carrying balances in the belief that it is a sound financial decision: stop immediately and take a moment to learn more before you make other poor financial decisions.