Customising QRadar interface, after issuing version 7.3.0, is rather a simple task. Users, willing to do it, don't need to have more skills than editing and copying files in Linux.
Obviously, don't do this in production systems. This is not supported. You do this on own risk only.
Simple edit the file below, but backup it first, if anything would go wrong you will be able to restore it.
# vim /opt/qradar/conf/localization/qradar.properties
and search for the property jsp.QRadar.QRadarLogin.description will give you the opportunity to change each of seven versions welcome message, which QRadar displays on the splash screen. It is also possible to edit this message in your own language. If you see a welcome message displayed in other than English, then edit one of the other files listed on a screenshot, specific for your own language.
These messages are around line 3250 in the default file, but it depends on language and version, so the best is to find the string first. Don't forget about the text in UTF-8 coding.
As a result, we can get a customised splash screen.
HTML tags added to the splash screen
If you want to go further, you can add HTML tag instead of text. As you can see on the screenshot I added the link to this website using <a link> tag.
Adding <img> tag can let you display a nice picture on the splash screen. In this example, I added the picture from my previous article about QRadar in AWS platform.
Have a lot of fun with customisation and don't break your box.