immigration history.. help please

hi guys i have been to united kingdom for four years , the last time i applied i was under 18 and i think i have made a mistake but i dont know if it will cost me or not

back in 2006 while filling the form i remember there was a question asking me do you have any friends or family living in united kingdom and i check no because although i had uncles and aunties living there but we did not have good term at the time with them

now i am going to apply soon as settlement case , marrying my cousin .
so would they have any objection over it ? or not ? or it does not matter

It is irreleavnt to your application whether you have any relatives in UK or not

so they wont check my previous application from in which i checked that i do not have

do they keep the previous forms with them ? if yes for how long !
or they wont just bother about all this since its settlement?

Was the cousin you intend to marry one of the relatives you didn't mention was living in the UK when you made your previous application to visit?
If so, you may well have a problem.