Dear emmy.campbell,
Greetings! Thank you for posting in Microsoft Community. We are happy to help you.
I'm sorry that you have issue when you save Office documents on Mac. I'd like to help you, please let us cooperate, we can work together to narrow down and resolve the situation.
Since this issue happens in Word, Excel and PowerPoint, I suggest you firstly check if your Office is still activated.
To check that, you may open Word, click Word menu from upper-left corner, if you see Activate Office option, click it and sign in your account.
If your Office is activated, you may click About Microsoft Word and check your Version and License information.
If your Office is still activated but you can't save documents, could you share with me following information? I will help you further.
1.The version of your Word application.
2.Please share a screenshot about When I go to file the save option is greyed out.
Look forward to your reply. Thanks for your time and cooperation!
We hope you stay safe and healthy always.
Sincerely,
Tina | Microsoft Community Moderator