With Joomla 3+ you can only assign a module to a page that has been created by a Menu Item. If you want a module to show up on just one page that is displayed on your site with a Category List Menu Type or Category Blog Menu Type, you will not see that individual article in the Menu Assignment tab for that Module.

If you assign it to the Category List or Category Blog Menu Item in the Menu Assignment page, it will show up on every page within that Category. This may not be what you desire for this module.

If you want this module to show up on only this one page, there are three ways to work around this situation. One approach is to use {loadposition custommodule} which place a module inside that individual article by its position name. Another approach is to create a new Menu that will only have this individual page. In the Article Manager you may still assign the Category to this Article, so it will still show up in a Category List or Blog, but it will also have a place to click the check box on the Menu Assignment tab for that module in Module Manager.

Option A: Use {loadposition customposition} to display a Module within the content of an Article

plugin-content-loadmodules

First you must be sure that the Plugin Content - Load Modules is enabled in Extensions -> Plugin Manager

In the Module Manager for the Module, there is a place to either select a position name from a drop down selection of pre-defined positions OR you can type in a UNIQUE position name in the text box. This position name needs to be unique and not identical to any pre-defined positions. Save and Close Module Manager.

Open up the Article in Article Manager and within the article itself, type in:

{loadposition customposition}

This goes into the content of the article where you want the module to appear. The position customposition is for this example, you will use your own unique name that you typed into the position box for that module. This can be typed in the WYSIWYG Editor or you can toggle the editor to HTML mode. Joomla sees the curly brackets and loadposition and recognizes that this is not normal content. The brackets and the code will not show up inside the Article. Save * Close the Article.

Back in Module Manager, you can assign a Module Class Suffix to the module if you need to style it in some specific way.

Since this is a custom position name, this Module will not appear anywhere but in that Article containing the line {loadposition custompostion}. You still need to have the page activated for that module in the Menu Assignment, though if you leave the setting at All Page, the module will only show up where that position has been called with {loadposition...}.

This option is good if you want the module inside the Article somewhere. It is not a good method if you want the Module to appear in a standard pre-defined position like position-3 or position-7, etc.

Instead of {loadposition...} you may also use {loadmodule...} to load any existing module into the content of an Article. The difference between these methods could be that if you have this {loadpositon...} inserted into multiple pages, then have several different modules with that same position assigned, for instance a different slideshow for each of these pages, you could then have styles that target those modules. Using {loadmodules...} would be better for instances where you only include an occasional module in an article. Using {loadmodule...} requires that you specify the type of module, ie mod_login and not the position name.

Option B: Use a new Menu with a Menu Item for the Article with the special Module

If you wish, you can create a new Menu that exists for these individual articles. As long as there is no Module with this Menu assigned to it, the menu will not appear anywhere on your web site. You need to create a separate Menu from your Main Menu or other Menus that you use for navigation so that this new Menu Item does not appear in other navigation. If you need to add other individual articles to this special Menu, you can. Name this Menu something like "Individual Articles".

Add a new Menu Item to this special Menu. Use the Single Article option and select your special Article that will have this Module shown. This Article can be assigned to a Category within Article Manager and even though it is in this Menu, it will also show up in your Category List or Blog.

In Module Manager for this Module, go to the Module Assignment tab and select None for all check boxes for the other pages to clear out. Now check the check box for this new Menu Item that you just created.

The Module will only show up on that chosen Article. It will show up on that Article when selected from a Category List or Category Blog.

This is the preferred method when you want a special Module to show up in a standard Module position. It can become cumbersome if you have multiple different Articles where you want individualized Modules.