Hi Sandro,
When Microsoft Word opens a new, blank document it uses the file named Normal.dotm as the template. Sometimes the Normal.dotm template is referred to by the expression "global" template because it affects all new blank documents opened in Microsoft Word.
In this case, our correspondent notes that new blank documents have the letter h displaying, which is unwanted. That means the Normal.dotm file was most recently saved with a letter h displaying. This is how you know the template needs to be changed.
You could not reproduce the issue because you do not understand the concept of Word's Normal.dotm template. I hope you take this opportunity to learn something fundamental about the way Microsoft Word works. It is an important concept to know, because it
governs how every new blank document is generated. It affects all users of Microsoft Word and is a cornerstone of understanding the product.
Restarting your Mac does not affect the global template.
Running in Mac OS Safe Mode does not affect the global template.
The version of Word is not relevant here. The concept of the Normal template has been in effect for about 35 years now.
The subscription or license type of Word is not relevant here. The concept of the Normal template is the same in all licensing types.
You need to know where the Normal.dotm file is saved in Microsoft Word. There is a default location, but the location can be changed by the user in Word > Preferences > Save. Most users do not change the default location, which is in a hidden directory.
Please see my reply to Manikanden for its location. I didn't ask Manikanden if they had changed that location because I think if a user knew how to change the location, they probably already knew what the Normal.dotm template does, how it works, and had a
specific reason to change the default location.
You should know that over the years that the Normal template file name has changed from Normal.dot to Normal.dotm as XML files replaced proprietary .doc files.
You should know that the Normal template file location has changed over the years and that the file location is in a very different file path in Mac and Windows versions of Office.
You also should know that the Normal template can be used to store macros and other customized content. Note in this screen shot of the Organizer tool that you can put a lot of different things into a Normal template. It is important to know that styles,
AutoText, Toolbars (in older versions of Word) and Macro Projects can all be stored in someone's Normal template. The Organizer tool can be used to move content into and from the Normal template. Because someone may have put such content into their Normal
template, never recommend that they delete a problem Normal template. Rename it instead and should there be a need to recover content from the old Normal template and move it to a new Normal template, the content will be available.

Yes, I know this is a lot to understand and take in. But there is simply no way to avoid learning how it works if you want to give advice about it.