How to set up Reply-to Sender email?

I'm not sure what you're referring to specifically about Reply to Sender option, but to change the email of reply to Sender, please follow:

1. Go to your Emails:

2. Edit your Notifier:

3. And on Recipients page you'll be able to change Reply-to Email address:

Please let us know if you have any additional questions.

Thank you!

See attachment - on this example, of course if I want to reply to the
sender, it would be to drrsm@augustafamilydental.com,
but when I hit reply, what comes up as a reply address is: Bob Merrill <
drbob112@gmail.com> - I am not sure why. Sometimes the reply address comes
up as noreply@jotform.com.
How can I get the email of the person filling out the form as a reply to
address?
Thank You.
*Bob*
...

I apologized but the screenshot you've shared is not showing. Can you please go directly to this thread (https://www.jotform.com/answers/839229) and then upload you screenshot using the "Insert/edit image" icon.

In order to reply to the submitter, you need to configure the Reply-to email in the notification wizard. Here in the wizard, click the "Reply-to Email" dropdown and select the "Your Email" which is the email field in your form where your user will type their email address.

Please check this related guide: Explanation-of-Email-Notification-and-Autoresponder-Settings

Hope that helps. Thank you.