How did World War II affect civilians around the world?
I would divide these effects into two main categories:
The effects of the fighting during WWII on the civilians could be summarized as follows:
1) Direct: these are the effects of bombing, shelling and direct occupation of cities and towns. In this case civilians were subjected to direct life threatening actions resulting in casualties (dead and wounded). Examples are: the carpet/fire bombings of towns such as Dresden, Tokyo or Coventry including the two nuclear bombings of Hiroshima and Nagasaki; the shelling of civilians areas for military purposes such as at Stalingrad, Manila in the Philippines or Monte Cassino in Italy; retaliation from occupation forces against partisans' attacks or racial motivated persecution such as the deportation and extermination of Jews in the concentration camps or the slaughtering of Chines civilians at Nanking.
2) Indirect: displacement of a great number of civilians (millions) due to invasions, occupations and deportation; we can remember the inhabitants of East Prussia and of the eastern parts of Germany escaping from the Red Army soldiers and the civilians eradicated from their countries and sent to Germany to work or in concentraton camps.
Destruction of houses, factories, railways and in general all kind of infrastructures needed to get food, shelter, sanitation and jobs; these destructions affected the civilians in a specific hard way because as a consequence they weren't able to obtain the necessary means to survive (considering that most of the goods/supplies were diverted to the army leaving the civilians, in particular in the cities, without food or medicines).
Apart for the ones I reported here there might be many other effects I am not aware of. For sure the civilians suffered the most in WWII.