Thank you for your help.
The Shortcut tab has four editable fields: Start In, Target, Shortcut Key, and Comment.
The "Target" field ends with: ...\Programs\Opera\launcher.exe.
I have tried with and without quotations around the path.
This does allow me to add "--disable-update" but I get an error where I have to say which program to use to open the file. Also it does update.
The "Start In" field ends with ...\Local\Programs\Opera.
I have tried with and without quotation marks around the path. It always gives this error message:
The folder '"...\Local\Programs\Opera" --disable-update' specified in the Start In box is not valid. Make sure that the folder exists and that the path is correct.
Deleting --disable-update gets rid of this error.
"Shortcut Key" will not let me add --disable-update.
"Comment" field allowed me to type --disable-update, but the game still didn't work.