The question is how to change your default search engine?

If yes go menu > settings > search > and select your search engine

Yes. I have done that several times. Duh...

Could you please send a screenshot of what the "Flights" icon looks like? When you search with it what domain are you sent to (ex: Google search will use google.com) ?

If "Flights" persists as your search engine even after changing it through settings it is likely that a malicious extension is responsible. Please review your extension list to see if there are any that you don't remember installing or seem suspicious.

You can open Firefox in Troubleshoot Mode so that all extensions are temporarily disabled. After making sure your search engine is changed back to whatever you are using, see if your search engine reverts to "Flights" at any point while using Troubleshoot Mode.

More information about search hijacking: https://support.mozilla.org/en-US/kb/what-search-hijacking

Run a full system scan with your Anti-Malware Software

Look for suspicious programs to your computer's add or remove programs

I only have the extensions shown in the second attachment.

Anti-malware is It is always running. Windows 11

Are you able to share a screenshot of the Flights website?

Have you installed any other software to your device recently?

I have no idea what their website is.

If you do a simple search using it, it should display a results page and have a URL.

https://search.yahoo.com/yhs/search?p=testing&hspart=iba&hsimp=yhs-synbg&param2=9dUI1n2R0BLDxNuWfiP4aSFOTltNdSPoIx38%2BUf%2FiXrvPdoGmStdlfwLFZYDvqkAfvapUGDUlfVlBewW80EIybo8zMXScMAyy6PDW%2F30AmU21shwuHER9T2%2BSK%2Fc9k3POg4g9XK1vqXy1%2Fs6k2psYCQMZTCYuWs7pwSADB%2F3dy8V%2FA5uZNOuKMIPHlDHIJg04pkkVcetCwhHCgnzWoDg2%2F7Awwc%2FLZgqdz0qVoKbYnI%3D&param3=HpCyCT2cXaKG4CVDR00rqo2oG1rIHjMij4XuH%2FTb7Mq5%2BD7nKHV7HbklYj%2BJk78Vl1bHUk3HfpxMZDjlAAPfEWOfXQjuGwb8o0L2pyCy4QQZ1OysQ2c2UJgVhYdBNjMwBaHnZamrbGBjkND8e27EsixJEyzI3VlzoEwMO%2BlEWj46rmooqRuwmMvXh2z%2B1gDW6W2lz4tdEccjfp%2BXX2S20Im%2FAMX8uBZ%2FVaBM1rjhdnRhQxxpMs4TYXWBWUNWGEMy%2FsqGPhDeDJ0ONM1J45oYmQ%3D%3D&type=f2%3A%3B.6850610d4680680b2811f3dcdca6be379af%3B5.ac48575a81c403f69399e8a8e3b01611ec4ceacc0ec96044db6480f2a94e02dfd4e142ff7a9d197bf1e44d2ea9da9634e01b74e71ec649454caab38483171

That is a search done with Yahoo. If you want use a different search engine, this support article should help:

https://support.mozilla.org/en-US/kb/change-your-default-search-settings-firefox

It does not show up in that list. See attached.

Is there anything you can show us that explains what and where this "Flights" is?

See attached file. It does not show up as one of my apps.

Would it be possible for you to show us a screenshot of what or where you are seeing "Flights"?

A web address or the "Flights" webpage would really help us to help you.

Yes. I have done that several times. Duh...