thrust line for engine and not mounting engine on this thrust line

Hello can someone please clear something up for me about the thrust line
I am interested in knowing what changes will happen if?
using a pusher type configuration for reference
I notice that many longez type aircraft vary a bit where the engine is
mounted in reference to the thrust line.
few align engine below line of main wing, but many align engine above this
line
my question is
is there some reference data I can read that would show
if you lower engine thrust line below main wing (this will happen) and to
compensate for the lowering of the engine you must (?) to correct this
problem created
and
if you raise engine above the wing line then you must do (?) to correct the
problem

what problems are you creating buy not aligning engine properly
and what is needed to be done to correct whatever problem you are creating

thanks been following this group a while but haven't seen any reference to
this
off line answers or explanations or help is welcome
thanks for any help tom laudato tom at youbuysell.com