RubyGems environment variables messed up :( - ruby-on-rails

Question

Please see below the print out from gem env. It appears as the INSTALLATION DIRECTORY, USER INSTALLATION DIRECTORY and GEM PATHS are screwed up. I attempted to install ruby version 2.3.0 for another project and switch over to that. I uninstalled ruby version 2.3.0 and switch back to ruby version 2.3.1. I noticed these RubyGems environment variables got screwed up some how :( Everywhere you see '2.3.0', I think it's wrong.
RubyGems Environment:
- RUBYGEMS VERSION: 2.5.1
- RUBY VERSION: 2.3.1 (2016-04-26 patchlevel 112) [x86_64-darwin15]
- INSTALLATION DIRECTORY: /Users/matthewsmith/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0
- USER INSTALLATION DIRECTORY: /Users/matthewsmith/.gem/ruby/2.3.0
- RUBY EXECUTABLE: /Users/matthewsmith/.rbenv/versions/2.3.1/bin/ruby
- EXECUTABLE DIRECTORY: /Users/matthewsmith/.rbenv/versions/2.3.1/bin
- SPEC CACHE DIRECTORY: /Users/matthewsmith/.gem/specs
- SYSTEM CONFIGURATION DIRECTORY: /Users/matthewsmith/.rbenv/versions/2.3.1/etc
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-darwin-15
- GEM PATHS:
- /Users/matthewsmith/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0
- /Users/matthewsmith/.gem/ruby/2.3.0
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- https://rubygems.org/
- SHELL PATH:
- /Users/matthewsmith/.rbenv/versions/2.3.1/bin
- /Users/matthewsmith/.rbenv/libexec
- /Users/matthewsmith/.rbenv/plugins/ruby-build/bin
- /Users/matthewsmith/.nvm/versions/node/v4.5.0/bin
- /Users/matthewsmith/.rbenv/shims
- /Users/matthewsmith/.rbenv/bin
- /usr/local/bin
- /usr/bin
- /bin
- /usr/sbin
- /sbin

Answer 1

if there are multiple versions installed, project dependent version must be set as default.
To handle multiple projects with different dependencies, gemset can be used. RVM support gemset. Alternatives are available for rbenv also.

Answer 2

Nothing is wrong. I can see that you are using rbenv, and that your global ruby version is 2.3.1
If you run in your terminal:
gem env home
It will return something like:
/Users/matthewsmith/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0
Apparently this line of code above tells that you have global rbenv version 2.3.1, and within li/ruby/gems folder you also have installed ruby version 2.3.0
In this folder .rbenv/versions/ will be all ruby versions you will about to install, or they are already installed.
When I install different ruby version let's say 2.3.0 I would do like this:
rbenv install 2.3.0 # install ruby version 2.3.0 using rbenv
rbenv local 2.3.0 # set ruby 2.3.0 to local project. It writes that version to a .ruby-version in your current directory
ruby -v # check your version to confirm that is 2.3.0 for a local project
gem install bundler
bundle install
Other options for installing ruby version are: SHELL and GLOBAL
rbenv shell 2.3.0 # Will temporarily change your Ruby version on your current shell. This sets the RBENV_VERSION environment variable in your terminal session.
rbenv global 2.3.1 # This will also change your Ruby version, but only the one you are using whenever no other version is specified, e.g. via a .ruby-version file or RBENV_VERSION variable.
NOTE! You don't need sudo to install gems. Typically, the Ruby versions will be installed and writeable by your user. No extra privileges are required to install gems.
reference
I hope it helps