When you use NutriAdmin to create a report, the report is intially in a not shared state. This means, it's not shared with the client, so the client cannot see it if they log in to the client portal.
The purpose of the Share button is to allow you to work on your draft, tweak it, and only share it with the client when it's ready. When a report is shared, the client gets an email notification, and they can log in to the client portal to see it.
Now, if you make changes to a report after you have shared it with the client, the client will be able to see those changes. That's because they already had access to the report and this report is shared.
If you want to create another document or make changes without your client seeing the new changes until they are ready, then you can create a new report. You can use the Save as or Copy buttons to duplicate the report if you want to make another version with similar content. This way, you can wait until the second version of your report is ready to then click the Share in portal button again.
Finally, anything you type in the Private Notes section of the client record is - as the name implies - private to you (and your team if you work in a team of multiple nutritionists/coaches). Clients can never see the private notes directly. That being said, when you generate a report, you can choose to add content from your private notes, so that's the point where you can tweak and decide which subsections of the notes you want to share, and also where you can format them.
So, the takeaway to remember is - before you click the Share button, clients cannot see your report. After you click the Share buttons, clients will be able to see the report - and any further modifications you make to that shared report.