The main recommendation when using Word is to be consistent when editing and saving documents in Microsoft Word.
When collaborating with others, it is recommended to edit the document online.
When editing documents online, the view will be different and will not be the actual “final” view. The true version of how the document will appear can be seen by going to the "View" tab and then selecting, "Reading View". To exit Reading View, select "Edit Word in Browser".
Additional Resources:
Word Help Center
https://support.office.com/en-us/word
Office365 Training Center
https://support.office.com/en-us/
Differences between using a document in the browser and in Word
https://support.office.com/en-us/article/differences-between-using-a-document-in-the-browser-and-in-word-3e863ce3-e82c-4211-8f97-5b33c36c55f8#__toc30962951