R still defaults to old installation after updating

Problem:

I have installed a new R distribution (3.5.0), which has installed successfully:

[user@f-001176055 ~]$ sudo yum install R-devel
[sudo] password for user:
Loaded plugins: langpacks, product-id, search-disabled-repos, subscription-
: manager
Package R-devel-3.5.0-1.el7.x86_64 already installed and latest version
Nothing to do

HOWEVER, when opening R, it continues to open the old version. How can I force the new version to open?