make a mountain out of a molehill
“Make a mountain out of a molehill” is a saying that means “to turn a small, unimportant issue into a big, important one.”
A mountain is huge; a molehill is small. The ancient Greeks had a saying, “make an elephant out of a fly,” which became a proverb in French and German. By the mid-1500s people in England were saying “make a mountain out of a molehill,” probably because “make,” “mountain,” and “molehill” all begin with the letter “m,” and alliteration helps make an expression fun to say and easier to remember.
Here is the idiom being used in a sentence:
David’s “broken arm” was only a sprained wrist, but he was making a mountain out of a molehill