Create a Pop up Message When Opening a Google Sheet
This is a video I created for my friend Diane who was looking to create a pop up message to appear when a Google Sheet is opened. (Note: it only appears for collaborators...those with view only access will not see it.)
Here is the Script you need to paste in the script editor (copy all of it!):
function onOpen() {
var ui = SpreadsheetApp.getUi();
ui.alert('This is my pop up message!');
}