2010 Toyota Landcruiser 2 head

I change valves & kits on head of my toyota land crusser 2010 model v 6 patrol engine after finsh maintinance ihear Crackling in the head engine, the Technical Mentioned to me that perhaps there is a lock in some of the valves Are valves unsettling made such as those voices or Crackling And how they are adjusting those valves please help.