phoenix framework - How to reinstall Elixir properly？ -

i use brew remove elixir --force , brew install elixir. elixir -v shows

erlang/otp 19 [erts-8.0.2] [source] [64-bit] [smp:4:4] [async-threads:10] [hipe] [kernel-poll:false] [dtrace]  elixir 1.3.2 

then use mix local.hex. mix hex.info shows

hex:    0.13.0 elixir: 1.3.2 otp:    19.0.2  built with: elixir 1.3.2 , otp 18.3.4.2 

finally, start new phoenix project. mix.exs shows

def project   [app: :b,    version: "0.0.1",    elixir: "~> 1.2",    elixirc_paths: elixirc_paths(mix.env),    compilers: [:phoenix, :gettext] ++ mix.compilers,    build_embedded: mix.env == :prod,    start_permanent: mix.env == :prod,    aliases: aliases(),    deps: deps()]  end 

why, mix.exs file shows wrong version of elixir, how can fix it?

everything ok elixir version. when generate elixir app mix new my_app have default 1.3 version, phoenix projects still use 1.2.