Whenever I type in a letter 't', it comes out fine. But when an 't' follows an 's', the two letter combine at the top.
How do I fix this?!
What font? If they're combining you must have a ligature option turned on and that particular font has a "ts" ligature.
That would be a "Discretionary Ligature" which you can turn off from the Character panel flyout menu.
If you want to remove all ligatures, turn off ligatures in the Paragraph Styles.
If you want to remove them only with specific combinations, make it via Character Style and GREP Style.