Jonathan Bardo

Note: This plugin only works with WordPress 4.2 or higher
This plugin will enable the site administrator to easily create an admin message present on all pages. The admin has the option to let the user dismiss the message for the duration of his session.

Admin User Message

This does just what I want. Thanks for making it. :)
It's definitely better than https://wordpress.org/plugins/admin-screen-messages
You might want to also tag it as:
https://wordpress.org/plugins/tags/admin-message



Perfect

Add message to users of your site. Choose wheter they can dismiss it or not.

chriscarvache

WelcomeUser! make it possible to add customizable welcome messages to you users based on their user roles. Inspired by sites such as eBay and Amazon, use this handy plugin for things such as:
<ul>
<li>Providing a set of quick links for your users</li>
<li>Displaying a friendly welcome message</li>
<li>Creating a call-to-action based on user role</li>
</ul>

WelcomeUser!

Add commonly seen user login links and welcome messages to the meta / utility section of your blog.

Admin User Message vs WelcomeUser!