It's not an accent it's a different letter е and ё. However, they are frequently printed as е and you just have know which letter it actually is.

You will not find 'ё' in the vast majority of contemporary Russian books, though it used to be a fairly common practice in USSR publishing to print this letter. These days it is mandatory for only books for nursery schools, kindergartens and language learners.

It is in most cases. 1. Because in USSR standard typewriters etc. didn't have ё. 2. Because most people who grew up rarely seeing ё in books are too lazy themselves to reach out thir finger to ё on the keyboard.

umlaut is only used in the nursery or the specialized literature. in most books it is absent, because it is bad printed on paper. But it has sound yo

Do not worry about it. This letter "ё" used not so often. And if you will say something not correct with "ё", do not worry, all the people will undarstand you.