hello Frenchgerman, i'm sorry but firefox 12 is over three years old, affected by many dozens of critical security vulnerabilities that got fixed in the meantime and unsupported. if you want to solve your problem there is no way around updating to a current version first: Update Firefox to the latest release

I'm sorry, but I will not use FF38 ... so what are the FF versions useable ?

without knowing what's your problem with version 38 this is difficult to answer...

It's the whole package that I don't like ... too complicated, not the add-ons that I like and use most. I don't like the lay out either ...

It's not a technical problem that I don't want to use FF38 ...

What about FF 21 or 22 ? (I mention these because I have the set-up links on my laptop ...)