rvm - default version of ruby - ruby

Question

I did this a few days ago:
$ rvm --default use 2.1.5
but then when I ran ruby -v today I got:
ruby 2.0.0p481 (2014-05-08 revision 45883) [universal.x86_64-darwin14]
Is there a better way to permanently set the version of Ruby I use?
==== UPDATE
$ rvm use
Using /Users/snowcrash/.rvm/gems/ruby-2.1.5
$ which rvm
/Users/snowcrash/.rvm/bin/rvm
$ which ruby
/Users/snowcrash/.rvm/rubies/ruby-2.1.5/bin/ruby
and output of rvm info (note that ruby has reverted back to 2.0.0p481):
$ ruby -v
ruby 2.0.0p481 (2014-05-08 revision 45883) [universal.x86_64-darwin14]
$ rvm info
ruby-2.1.5:
system:
uname: "Darwin w.local 14.0.0 Darwin Kernel Version 14.0.0: Fri Sep 19 00:26:44 PDT 2014; root:xnu-2782.1.97~2/RELEASE_X86_64 x86_64"
system: "osx/10.10/x86_64"
bash: "/bin/bash => GNU bash, version 3.2.53(1)-release (x86_64-apple-darwin14)"
zsh: "/bin/zsh => zsh 5.0.5 (x86_64-apple-darwin14.0)"
rvm:
version: "rvm 1.26.9 (latest) by Wayne E. Seguin <wayneeseguin#gmail.com>, Michal Papis <mpapis#gmail.com> [https://rvm.io/]"
updated: "8 days 7 hours 2 minutes 42 seconds ago"
path: "/Users/snowcrash/.rvm"
ruby:
interpreter: "ruby"
version: "2.0.0p481"
date: "2014-05-08"
platform: "universal.x86_64-darwin14"
patchlevel: "2014-05-08 revision 45883"
full_version: "ruby 2.0.0p481 (2014-05-08 revision 45883) [universal.x86_64-darwin14]"
homes:
gem: "/Users/snowcrash/.rvm/gems/ruby-2.1.5"
ruby: "/Users/snowcrash/.rvm/rubies/ruby-2.1.5"
binaries:
ruby: "/usr/bin/ruby"
irb: "/usr/bin/irb"
gem: "/usr/bin/gem"
rake: "/Users/snowcrash/.rvm/gems/ruby-2.1.5/bin/rake"
environment:
PATH: "/Users/snowcrash/.rvm/gems/ruby-2.1.5/bin:/Users/snowcrash/.apportable/SDK/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/opt/local/bin:/opt/local/sbin:/Library/Frameworks/Python.framework/Versions/Current/bin:/usr/bin:/Users/snowcrash/Library/ec2-api-tools-1.3-24159/bin:/Users/snowcrash/bin:/Users/snowcrash/Library/android-sdk-mac_86:/Users/snowcrash/Library/android-sdk-mac_86/platform-tools:/Users/snowcrash/Library/bin:/usr/local/mysql/bin:/usr/local/bin:/Library/PostgreSQL/9.1/bin:/usr/local/sbin:/Users/snowcrash/.rvm/gems/ruby-2.1.5/bin:/Users/snowcrash/.rvm/gems/ruby-2.1.5#global/bin:/Users/snowcrash/.rvm/rubies/ruby-2.1.5/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/Users/snowcrash/.rvm/bin:/Users/snowcrash/bin/gsutil:/usr/local/graphviz-2.14/bin:/Users/snowcrash/.rvm/bin"
GEM_HOME: "/Users/snowcrash/.rvm/gems/ruby-2.1.5"
GEM_PATH: "/Users/snowcrash/.rvm/gems/ruby-2.1.5:/Users/snowcrash/.rvm/gems/ruby-2.1.5#global"
MY_RUBY_HOME: "/Users/snowcrash/.rvm/rubies/ruby-2.1.5"
IRBRC: "/Users/snowcrash/.rvm/rubies/ruby-2.1.5/.irbrc"
RUBYOPT: ""
gemset: ""

Answer 1

Your PATH contains /usr/bin multiple times, the first of which is before /Users/snowcrash/.rvm/rubies/ruby-2.1.5/bin, so the system provided ruby is added first.
You seem to have a lot of entries in there - review your shells initialisation files (.bashrc, .bash_profile etc) and check anything that manipulates $PATH

Answer 2

What does stuff like rvm use, which rvm or which ruby say? That looks like the system Ruby, which to me means you don't have rvm properly installed and you opened a new terminal session and got the system version.
Or, the command was entered wrong. rvm use --default 2.1.5
After that, rvm list will show it marked as default.
(nick#blerp)-(~)
(507)⚡️ rvm use --default 2.2.0
Using /Users/nick/.rvm/gems/ruby-2.2.0
(nick#blerp)-(~)
(508)⚡️ rvm list
rvm rubies
=* ruby-2.2.0 [ x86_64 ]
# => - current
# =* - current && default
# * - default
You could always reinstall rvm (doesn't hurt to reinstall on top) and make sure the path settings are in your shell dotfiles.