Thanks, @Teodor_Bogdanov1
Ok, so rather than just give you the answer, I figured readers may learn more if I explained my process of how I found the answer.
1. Finding the file
After installing the theme, I went into Developer Mode and enabled the following option in System > Configuration > Developer > Debug
- Enabled Template Path Hints for Storefront = Yes
- Then cleared the cache.
When viewing the Frontend, this gave me a hint of the filename that was responsible for the output:
app/code/Infortis/UltraMegamenu/view/frontend/templates/categories.phtml

After finding the file, I disabled “Enabled Template Path Hints for Storefront” to make it easier to read the Google Chrome Inspect Element output. Otherwise it looks all messy whilst this feature is still enabled.
2. Finding the code
Then I used Google Chrome Inspect Element tool on the word “Categories” to help me get my bearings in the categories.phtml
file.
I then opened the categories.phtml
file to see if I could find this bit of code. Once I found my bearings (in this case block-title
) it gave me all of the breadcrumbs I needed to find the anwer:
<div class="block-title">
<strong><span><?php echo $title; ?></span></strong>
</div>
So, the “Categories” label on the Frontend is being created by a variable called “$title
”. Having found this, I worked my way back up the page to find what “$title
” was being created by and found this line:
//Sidebar block title
$title = $block->renderBlockTitle();
This told me that the label was being pulled from another variable called “$block
”. So, I scrolled further back up the page and found this line:
$helper = $block->getHelperData();
So a “$helper
” is normally used to “help” get variables and is seen a lot in Theme Files. Therefore, this gave me the idea that the value of “Categories” is stored as a setting in the Database. And if it’s in the Database then it must be a setting in the backend.
3. Answer
So having already determined that the settings were related to the Menu (based on the location of the categories.phtml
file) and the variable was most likely a setting in the backend, I went to System > Configuration > Infortis Extensions > Menu and found this:
So I changed it and cleared the cache:

Final Words
Yes, I could have just given you the answer, but no-one will learn anything that way. I hope this helps 