How to adjust form theme and text color

I have cloned your form and modified it:

https://form.jotformpro.com/72416563970966

You can clone it:

How to Clone an Existing Form from a URL 

Or you can you try adding this CSS code (for the text colour to show)

.form-textbox {
    color : black !important;
}

How to Inject Custom CSS Codes

Also you can choose a different single choice component:

Please follow this guide to add your form to Facebook:

Adding a Form to Your Facebook Page