I've been employed for five years my income is low.  I'm a home owner I've lived at the address 8 years my credit cards are are both under 40 percent under limit I was told by bank my earnings will not stack up to pay for card payments how does bank know my earnings also tried to compose message but it says 11 content items don't understand appreciate your assistence

no ccj late payments or defaults hence I used Vanquis and capital one to build credit but now would like to apply for normal credit card but not sure to send my cards back and apply for new ones or keep them and apply do you know best action to take 

Pay off the current balances first, before applying for a CC with better interest rate.

It may be that as part of your application you gave your earnings information.  Credit records don't have the information.