Q. How can I avoid signer 2 and signer 3 from tabbing through form?

Hello!

The problem as you describe it suggests that all of your fields (or at least the ones that you have a problem with) are defined as "Anyone" fields.  This means they are not explicitly assigned (eg: Signer1), so unless the field has some content inserted, the field remains viable for the next recipient.

Creating forms in Acrobat, and using the automated field placement feature, will produce fields assigned to "anyone" by default.

If you open one of the field's properties box, if should look like this (assuming you have converted the form to an Adobe Sign Form):

What you need to do is change the Participant Role field to the correct recipient for each field.  Probably Signer1 based on your description.

Given the number of fields in the images you have provided, this looks to be a lot of clicking and setting of values.

So, before diving in and changing all of these fields, I would recommend trying the in-app Adobe Sign authoring tool.

This feature has recently added field detection, and the default value for the discovered fields is Participant1 (essentially Signer1).

As long as the field detection finds a majority of the fields, this could save you a lot of time.  If it does not, abandon the process, return to the PDF doc, and set the values manually through PDF.