Current Form Version (single form)

Because a few other people in that old thread are also having trouble, I will try to answer this with a little more expansion. 

All of your Nintex Forms for a given site are stored within a hidden library called NintexForms. You can find it by replacing everything in the URL after the site you're currently in with the name "NintexForms". Here is an example of what your URL should look like:

Once you are in the Library, do yourself a favor and click on the three dots, then Modify This View:

In the View Settings, find and click on the checkboxes for both [Version] and [FormListId]:

(note: they are shown here at the end of Title because I have already checked them. But if you're modifying the view for the first time, you will need to find them amongst the other columns! just scroll down a bit ;))

Cool, so now you have a Library that shows you a bunch of non-sensical GUIDs for Form Construction Data, Version, and FormListID... what good is that? 

Well if that FormListID is actually a reference that ties the Form xml file to whichever SharePoint List / Library the Form is actually associated with. We can use this information to pull the current Version number into our Form when we render it by using a Lookup Formula. But first we'll need to make sure we have the List ID of any given list where we are wanting to show this for a Form. 

There are a few ways to do that

Method 1. When you open up the Form Editor, you'll notice that in the URL bar there is a long string of characters after the term "ListFormDesigner":

Text Example:

Well, that string of alphanumeric characters "%7BXXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX%7D" is the ListID. It should be noted that the %7B and %7D are both stand ins for different characters, "{" and "}" respectively. That means that your final ListID should look something like: 

Method 2: Clicking on the Library Settings will take you to a page of settings where the URL will also show the ListID much like how it does above:

If you're not able to easily see where those brackets should go, you can throw the entire URL into something like the URL Decoder (https://meyerweb.com/eric/tools/dencoder/) and click on the Decode button:

Now that you know the NintexForms list and your List ID, all we need to do is create a lookup on the Form in question. Here I've made a Calculated Control:

Settings of Calculated Control:

And formula:

Note that YOUR LISTID WILL BE DIFFERENT! It's different for every list, on every sharepoint, everywhere in the world!

However, when we now preview our form I can see:

Which indeed matches what the designer tells me:

I hope that this takes any of the guess work out of getting this to work in your own forms. 

Please mark this answer as the solution if it has solved the issue. 

Thank you

As far as I know, javascript doesn't work in mobile forms 😞 

It's been a long standing request, but will likely never be implemented 

https://nintex.uservoice.com/forums/229417-6-nintex-mobile-app-studio/suggestions/8780188-javascript-in-mobile-forms