Is this with opening a new tab by clicking the plus button on the Tab bar?

You can try to set this page as the home page and middle-click the toolbar Home button on the Navigation Toolbar to open this page in anew tab.

Custom New Tab: https://addons.mozilla.org/firefox/addon/custom-new-tab/

No, i have this problem at all tab. I try to better explains - I open firefox (my start page is google) - I want make a search, i begin to write my search in writting area - After a few letters, search switches to the address bar and Letters what I write are consequently in address bar - I oblige to select once again the google's writting area else when i valide firefox directs me to a single page depending on the song of words I typed in the address bar

Start Firefox in Safe Mode to check if one of the extensions (Firefox/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: Firefox/Tools > Add-ons > Appearance
• Do NOT click the Reset button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

If it works in Safe Mode and in normal mode with all extensions (Firefox/Tools > Add-ons > Extensions) disabled then try to find which extension is causing it by enabling one extension at a time until the problem reappears.

Close and restart Firefox after each change via "Firefox > Exit" (Windows: Firefox/File > Exit; Mac: Firefox > Quit Firefox; Linux: Firefox/File > Quit)

In safe mode, the problem is always there. When make test i I finally observed that the problem was only present on a new tab as you said. the address bar becomes a search bar. But I can not remove this option in the customization menu