Qt installed in two places; wrong one takes precedence

My system is running Ubuntu 16.04 LTS. I seem to have installed Qt in two places. 4.8.7 is installed in /usr and 5.5.1 is installed in my home directory for reasons which probably seemed sensible at the time. $ /usr/bin/qmake -v QMake version 2.01a Using Qt version 4.8.7 in /usr/lib/x86_64-linux-gnu $ ~/Qt/5.5/gcc_64/bin/qmake -v QMake version 3.0 Using Qt version 5.5.1 in /home/jsd/Qt/5.5/gcc_64/lib $ which qmake /usr/bin/qmake Qt Creator sees the home-directory version and thinks it's running 5.5.1, but when it runs qmake in the build process it runs the 4.8.7 version and minor annoyances follow. How can I clean this up? Also, is it normal for Qt to be installed in my home directory? **Edit:** The reason this was an issue is Qt Creator was ignoring CONFIG += c++14 and refusing to allow C++14 syntax like auto foo = [](const a, const b){return a when compiling with Clang 3.7, which should support C++14. qmake only supported CONFIG += c++14 since 5.4 hence I thought the problem was my old qmake version.