Maybe you really have 5 unread messages in your account.
I have much more than 5 unread messages in my account. But shouldn't the icon show the number of
new unread messages?
increase the number of synchronized messages in AquaMail (long press account name -> Options and folders -> number of synchronized messages. Or FAQ)
I'm sorry, I don't find that option under "long press account name -> Options and folders". There's only "Kontoeinstellungen (account setings)", "Verfassen und Senden (Compose and Send)", "Vorab laden (load in advance)", "IMAP options" and "Folders". Where should I search for "number of synchronized messages"?