I have just watched the 49th episode of Dragon Ball Chou.
Trunks returns from the future in order to seek help for defeating Goku Black. During his speech, he explains how he prevented revival of Majin Buu by killing Dabura and Babidi.
How could this be possible? Haven't Dabura and Babidi been killed in the current time line? How can someone who is killed exist in the future? Can you explain the logic here?