In the top righthand corner, there is a drop down box that is populated by a list of domains set-up on that server. It seems on my installation the listing of domains is not done alphabetically but by oldest first.
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With just a few domains, that isn't an issue but if you have a lot then this could become a problem.
You can go to the "Settings" page in Softaculous enduser panel i.e. (the icon on upper right corner that looks like "wrench") and then select the "Sort domains alphabetically" checkbox and click on the "Edit Settings" button.
This will display the domains list sorted alphabetically.