I recently took the TOEFL test and my score didn't satisfy me, even the result is above the minimum requirement for almost all universities. If I will retake the test and send my new score for graduate admission, will the admission committees always choose the best score between two attempts or is it possible that only the recent score will be taken into consideration? I want to clarify it before retaken decision, in case if my score will decrease.
Unless your score is significantly low in one particular section (for instance, having a 105 with 30 on all sections but a 15 on Speaking) or if the committee has a strong reason to doubt your English skills, I don't see why you should worry about resubmitting TOEFL score. You will be making far better use of your time strengthening other parts of your application (i.e., SOP, GRE, etc). Given a sufficiently strong application, even if they doubt your ability to communicate in English, some schools will interview the applicant via Skype/phone to establish whether their English is sufficient, and not automatically discard the application.
The TOEFL score serves, in general, to establish that you have a basic ability to communicate and work in an environment where English is the main language. Meeting the usual 100+ TOEFL score for graduate applications is sufficient and higher scores are not usually heavily weighted.
To more directly answer your question about which score they will consider, that will strongly depend on the school. You can e-mail them directly to know how they will consider multiple TOEFL scores. I suspect it would be analogous to the GRE (i.e., some departments choose whichever has a higher total score, some schools pick whichever is higher by section, some schools pick the latest, some schools analyze holistically).
Note: the answer to your question may depend on your field. I am in engineering.