To set SearchGPT as your default search engine in Google Chrome and Edge:
#1: You can do it vide a SearchGPT Extension:
Visit the SearchGPT extension page on the Chrome Web Store.
Click “Add to Chrome” and confirm by selecting “Add Extension.” Set SearchGPT as Default:
After installation, the extension will automatically set SearchGPT as your default search engine. You can now perform searches directly from the Chrome address bar, and SearchGPT will handle your queries.
Opera:
Opera will not allow you to set a new default search engine because they make money off every search with Google. However, you can add a new search engine in Opera easy enough by going to Settings, then Search engine, then Manage search engines and site search:
Then add a new search engine. I suggest add it as shortcut S:
the string need is: https://chatgpt.com/search?q=
Setting Default Search in Microsoft Edge
Edge will require you to jump through some hoops to use the Chrome extension:
Just click the “Turn On” and it takes you to the Extensions page where you will have to finally turn it on:
And just when you think you finally have it done – it prompts you one more time:
Vivaldi
Go to settings and click on +at the bottom of the search engine list. Enter the new search engine definition with the string: https://chatgpt.com/search?q= 
As the CEO and founder of Pubcon Inc., Brett Tabke has been instrumental in shaping the landscape of online marketing and search engine optimization. His journey in the computer industry has spanned over three decades and has made him a pioneering force behind digital evolution. Full Bio
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