When I say the word "Yeah," I mean, "I agree with you."
When my husband says the word "Yeah," he means, "I heard what you said."
Would you believe I didn't figure this out until we'd been married for about sixteen years?
All that time, I was getting frustrated because I'd tell him something or ask him something, and I'd think he was agreeing with me. Then when it came up later and it turned out that he did not agree with me, I felt like he wasn't listening to me or that he was changing his mind all over the place. One day, like a bolt of lightning out of the sky zapping me in the forehead, I realized that we were speaking two different dialects. I said to him, "When you say 'Yeah', what does it mean?"
He had a very confused look on his face when he said, "It means that I heard you." I explained what it means to me, and suddenly, an issue we'd been struggling with for sixteen years was resolved. Now when he says "Yeah," I ask, "Do you mean that you heard me or that you agree with me?" This gives us the chance to understand each other better and avoid disagreements later.
I'm sharing this because it's pertinent to your writing. Different regions use different words and phrases in different ways, and if you're using a term that doesn't have a universal meaning, you could confuse your reader. They might think you mean something else entirely, and that might change the meaning of the story for them. As you write and as you edit, seek to be very clear with what you mean so you're all on the same page (ha ha). A confused reader is not a repeat customer.