I have a php display errors,

PHP error messages may appear on the website (the system told me during the installation).

Does anybody know how and where i can change the settings? Solution?

That's a server setting actually. You can disable that via htaccess, php code or probably easier somewhere on your host's webspace backend. On a proper server it should actually be off by default.

Thanks,
as the error message arrived during installation, it is not off.

Found something:

file "php.ini"

Command in it "display_errors = Off;"

I guess this "php.ini" must be uploaded into the folder in which the gallery is, right?

Yes, the php.ini and that command would be correct. It sadly depends on how your host has setup your webspace. Some allow php.ini files for such settings even specific for directories, other need it via htaccess (or both). Others may not allow it at all or only via their backend. You host probably has some FAQ about that.