Spell check auto corrects lower case letters to capital letters in the middle of a sentence

I'm working on a poem for a plaque. After i spell check the text in the paragraph i am working on the spell checker auto capitalizes the y in your in the middle of the sentence! i have checked every setting i can think of and i have come up empty. i can change it back to lower case, and its fine. its just annoying.  Any help would be appreciated!