SELECTED ANSWER
replied on November 20, 2020
I got this right. On each form I used the custom html field and pasted this code
<p>
<a href="http://servername/landingpage" style="color: #0000EE; padding-left:450px"> Click Here To Return To Landing Page</a>
</p>
For the Thank you page I clicked the "Show a follow up message" on event completion tab then pasted this code on the html tab
<div style="text-align: center;" align="center"><div style="margin: 25px auto"><h1 style="font-size: 150%; margin-bottom: 30px;">Thank you!</h1><div>Your form has been submitted. <br> <a href="http://servername/LandingPage" style="color: #0000EE;"> Click Here To Return To Landing Page</a>
<p></p></div></div></div>