Keyboard shortcut to fill forms
The default shortcut fills the current page without opening the popup: Ctrl+Shift+U on Windows and Linux, Command+Shift+U on a Mac.
Change the keys
Open the Autofill Forms popup. Next to the shortcut line, press Change. Chrome opens the extension shortcut page. Set a new combination for the fill command. If Chrome says the keys are taken, pick another pair.
When the shortcut does nothing
It fills the active tab with the selected profile. It cannot run on Chrome’s own pages or on the Chrome Web Store. If no fields match, the page stays as it was. See when a page will not fill.