Firefox will nearly always where possible and applicable try to retain changes and customisations made. Is there anything in particular that concerns you ? You appear to be on only Firefox12, instead of Firefox 20 so you have a lot of catching up to do,and by using an outdated Firefox are increasing the risk to your system and personal data. I strongly recommend you upgrade without delay. Sometimes extensions may not be compatible, or you may be asked to confirm you want a particular extension to continue by default. Occasionally things are by default blocked due to security issues.