How to make text boxes editable on a form?

I'll try to make this simple to follow.

I have created a form in Adobe Acrobat DC. I've inserted text box fields on this form. I've made the form "secure" to not allow editing outside of entering text into the text fields.  BUT, I need clients to have the ability to change the font type, size, and color in those fields.  That is the only thing I'd like clients to have the ability to change.

When I open the form/document, I am only able to type into the text fields but if I do "CTR+E" I get a gray properties box that says "No current selection".

What am I doing wrong?

I am all updated, no updates available.