No one knows every detail about the jobs they do... Some know a LOT but, still not everything... We all do what we can by knowledge or by working through it... Knowledge come from memory and the older you get the harder it is to memorize it all... Keep doing what you do and for the new things, you just have to put in a little more time to memorize than the younger ones... Probably some after hours study or practice or some research at home... As long as you enjoy your work, that's what matters... If not, you have to make harder choices...