Will there be any copyright issues if I make a short movie with EXACTLY the same narrative structure as the Hollywood movie "Memento", but with totally different story? Also, do I need to credit them (the makers of Memento) for the narrative structure of my short movie?
Yes, you can. But I am not a lawyer, and very powerful lawyers may think otherwise, and while you may win a lawsuit over it, it will be expensive.
From an educational lawyer copyright blog https://library.osu.edu/blogs/copyright/
While the requisite level of creativity is low, copyright will not protect ideas (including narrative structure or general plotlines), concepts, or common themes.
In addition, there may be situations in which there are only a limited number of ways to express an idea. If this situation exists, the idea merges with the expression, and the expression becomes uncopyrightable (this is referred to as the merger doctrine in copyright law). Similarly, copyright will not protect standard expressions or stock characters or events that are ordinary to a particular subject matter (this is referred to as the scènes à faire doctrine in copyright law). The structure of a knock-knock joke, for example, cannot be copyrighted.
The general concept is that Expressions of an Idea are copyrightable, but not the general idea itself. Which is why you could have multiple movies about blowing up an Asteroid, or any number of nearly identical love stories, or comedies, or anything.