My email keyboard is acting strangely

[AC Question]

I have a Samsung Galaxy S5 Neo. Something has happened with the keyboard, but only when I write email in my phone, not when I text. In email, the keyboard doesn't capitalize the first letter of a new sentence, even though it does when I text. Also, the keyboard replaces the numbers I write with other symbols, but again, only when I'm writing email. What could the problem be?