When I close Opera, CClean automatically cleans it. When I close any of my other browsers--Vivaldi, Firefox, Chrome, or IE--CCleaner will pop up and tell me that the browser has closed, and, for a few seconds, if I wish, I can click on the blue "Click here to clean" in order to clean the browser.
Where is the setting in CCleaner to automatically clean a given browser when it closes? The image I've attached is of the CCleaner gui with the browser cleaning options showing, and you'll notice that the settings are identical for Firefox and Opera. Superimposed on that image are the CCleaner messages that appear above the system tray, the top one being what appears when Opera is closed, the other one being what happens when Firefox is closed. It seems like I have a vague memory of telling CCleaner to automatically clean Opera at one time, but, if so, I can't find where to do so in its gui.
By the way, I do not like the relatively new gui, with the "custom" and "easy" clean settings. I prefer the old-fashioned one. Maybe Piriform should poll its users.