"Push" Notifications

I believe they are called “Push” Notifications.  The small window that opens in the bottom right and makes a sound as you get a new email.  

I am hoping to change the settings.  Does anyone know where I might find them?

Push notifications have to do with the way the server lets eM Client know when there are new messages so that it can download them. eM Client uses IDLE (PUSH) IMAP to communicate with the server but that cannot be configured.

It is not the same as the popups you see in your OS when new messages arrive in eM Client. To change the new mail notifications got to Menu > Tools > Settings > General > Notifications.