I have Python 2.7.3 and 3.2.3 installed on my Ubuntu 12.04 64bit (by default?). When I type "python", I want python 3.2 instead of 2.7.

Changing symlink "python" to link to python3 seems to cause big problems. Why is that and is there a way to do that?

lrwxrwxrwx 1 root root       7 Sep 28 19:15 python -> python2

lrwxrwxrwx 1 root root       9 Jun 18 13:26 python2 -> python2.7

-rwxr-xr-x 1 root root 2993592 Apr 10 02:46 python2.7

-rwxr-xr-x 1 root root    1652 Apr 10 02:46 python2.7-config

lrwxrwxrwx 1 root root      16 Jun 18 13:26 python2-config -> python2.7-config

lrwxrwxrwx 1 root root       9 Apr 10 17:12 python3 -> python3.2

lrwxrwxrwx 1 root root      11 Apr 10 02:13 python3.2 -> python3.2mu

-rwxr-xr-x 1 root root 2949952 Apr 10 02:13 python3.2mu

lrwxrwxrwx 1 root root      11 Apr 10 17:12 python3mu -> python3.2mu

lrwxrwxrwx 1 root root      16 Jun 18 13:26 python-config -> python2.7-config

I linked python to python3:

sudo ln -fs python3 python

It worked but later it forced me to change the link back because Ubuntu seems not much responsive and I can't run most of the applications any more, such as Variety, Spyder, Okular, Software Center, etc.

Edit:

Yes, the 2 answers in the marked duplicate question Problems upgrading to Python 3.3 and setting up Django addressed half of my question, and the question itself doesn't seem to be related to my question when I try to search for an answer. I doubt anyone would realize the answer is below that question.