S2Member is the best plugin for WordPress-driven membership sites. If you use S2Members and want to customize the button text which says "Submit Form" to something else, then you have a few choices.
The easy way to change the Submit Form button
I assume that you don't have a child theme and further more, that you didn't make any customization yet. Ether way, you can change the text string from Submit Form to "Create Account" quickly. Here are the steps:
Use your FTP program (I am on a Mac and use Cyberduck but any FTP client will work the same) and navigate to the plugins directory. From there, go to "s2member-pro" and open the "forms" directory. At the bottom, you see php pages that begin with paypal and stripe.
Let's say you are using stripe. To change the button text that reads "Submit Form" to Create Account, simply open the file "stripe-registration-form.php" and towards the bottom, on line 159 you see php echo esc_html(_x("Submit Form ...
To make this easy, use any free code editor like Atom (my favorite) or Brackets and simply replace that text string to what fits your page better.
Here is my registration page: Little Composers Create Account
If you open it, you'll see right away the the button text says "Create Account".
Document your changes and the steps you've taken to make them
The bad news first. When the plugin gets updated, your changes will be overwritten. Many advanced users have child themes and heavy modifications added to their functions.php file. In time, you will do that too but for now, simply document the steps to change this. It is quick and there is no need to waste hours with finding a plugin that translates text strings and adds a lot of bloat to an already heavy WordPress install.
My fix is "old-school" but S2Members does not get updated very often. Once a year? What I am trying to say is this. If you are careful and plan your updates, then you'll know what to change. Have backups of the php files you change and a text file that documents "what" you have changed. This way, you can always revert or tweak your changes. No need for a plugin. No need for a child theme. A few minutes of work and everything is like it is supposed to be.
Helpful software that make system administration easy
Editing php files is not hard. DO NOT change anything that you don't recognize. Look out for the word "echo" which, in simple php terms means to write something on the screen. A good code editor will make searching for the text strings (fancy talk for words) quick and easy. Speaking of code editors, here are two I recommend highly.
I use Atom and a handful of extensions such as Emmet for all my WP and HTML / CSS editing needs.
Brackets is also open source and does the same thing Atom does. Ether editor will easily allow you to change the Submit Form button text to Create Account or what every else you want it to say.
Cyberduck is available for both, Mac and Windows and my favorite FTP client. I work a lot with a Wacom tablet and Cyberduck never drops directories or files in wrong places as Filezilla does.
- Image optimization
If you have a Mac, then find ImageOptim 2, put it in your dock and drag EVERY png or jpg file on it before you upload it to be used in your web page.
If you are on Windows 10, then you have a similar choice by the name of Riot (Radical Image Optimization Tool).
I can't imagine doing my job without these programs. WordPress is too amazing for words and without it, most of us wouldn't have a membership site or any need for s2Member or similar plugin.
I hope this helps you with changing the text on the s2Member pro forms. I know that from time to time, I too will look up stuff that I am documenting for all of us.
Your feedback, suggestions and comments are always welcome. Thank you for reading.