stop giving grammar errors for contraction words
Word has been giving grammar errors for the contraction words, such as
-suggesting that "isn't" should be replaced with "is not"
-"doesn't" should be replaced with "does not"
Wanted to add...
This is not an issue with the software, or the grammar checker. It's a personal issue.
Change your grammar checker's settings if you want it to "stop giving grammar errors for contractions."
It's because you have "Grammar & Style" selected. Contractions are "informal writing." You should not be using them in academic, scholarly, or formal writing - except when discussing the topic or reproducing text, idioms, quotes, etc. that include them.
Otherwise, they should not be used.
If you have Office set to check style, and the style it's checking is Formal or Academic (or anything similar), then it should and will flag contractions and ask you to expand them. They should not be used in that kind of writing. It's bad style, and when read aloud, can be ambiguous... For example, won't vs. want (they are pronounced the same by many people).
If you are writing for school, or any type of official/formal setting/recipient, then you should not be using contractions.