Open Opera Maximized in Linux Mint 18.3

Okay, I just reinstalled Linux Mint 18.3 (after a brief experience with Linux Mint 19.2), and I forgot how/where I made the changes to open Opera maximized (full-screen mode).

Where do I make the changes? How do I make the changes?

My apologies for not writing this down the first time. :(

Thanks, guys.