Why do you think there has been no declared war since World War II, yet the US has been almost constantly engaged in military action? What is the difference between Congress “authorizing the President to use force” and declaring war? Who bears more responsibility in each case? Which, if any, seems to lead to better outcomes for the US?

Yes,  US constantly engaged in military action.

Explanation:

Yes, there has been no declared war since World War II, yet the US has been almost constantly engaged in military action because United States want to control the whole world and main his supremacy. So for that reason, United States is constantly engaged in military actions which cost them a lot on the economy. Congress “authorizing the President to use force” means to use the force for defending its own interests while declaring war is a full fledged war against country or community. President bears more responsibility in each case because he is the head of the country. Declaring war needs more resources and money for the war and soldiers which greatly effect the economy of the country while using force for a particular mission does not need more resources and money so using force is better than declaring war.

can you post options so i can ?

yes i think there would be volunteers