I've had yellow stools, too. And I mean YELLOW!!! I've also had Green. And Pink. Yes, Pink.
turns out the Pink was from too much watermelon sherbet.
When I had the yellow ones, I did get tested and nothing wrong. The doctor wasn't concerned but I got tested anyway, and all was fine. Turned out it was a combination of things I was eating and anxiety. I do have allergy issues and sometimes the mucus goes into the stomach and can turn the stools different colors, including white!
My physician explained that any difference in stool softness/hardness/color is actually called Diarrhea.
He said diarrhea is not just watery stools, but any change in the stool, be it color, firmness, number of times, etc.
Think of it this way. One day you wake up with a cold that you didn't have the day before.
Today you pooped yellow that you didn't have yesterday. But, you're worrying about it. Think of it as a cold. It will pass. For real.
I know from past experiences I used to really worry about every color change. Until my doctor set me straight. I trust him. He also said that nerves can definitely change the color/consistency and amount of stool (diarrhea) that we have. Please know that you are not alone. And that you are fine.