Why was the united states reluctant to enter world war ii, and why did the government change its mind?

The united states as a powerful nation wanted to maintain its reputation.With propaganda over the US being "cowardly" the US therefore were "encouraged" to engage and help the allies

America was reluctant to join WW2 because as a nation they were just beginning to recover from the Great Depression and had just recently lost troops in WW1, and the reason they changed their mind was because of the German's decision to resume submarine warfare and the Japanese pearl harbor bombing.