If you use your Qi credit card for six months, you can apply to increase the fixed limit.

Citibank's tips for increasing your balance:

① Swipe as much credit as possible;

② Spend as many times as possible;

③ Type of consumer merchant more;

④ Maintain a good credit record;

⑤ Take the initiative to apply for an increase in the limit;

⑥ Consider a temporary limit in case of emergency.