Qt5 installation and path configuration

Replace Default Qt version paths in:

/usr/lib/x86_64-linux-gnu/qtchooser/default.conf
or in newer releases /usr/lib/x86_64-linux-gnu/qt-default/qtchooser/default.conf:

/opt/Qt5/bin
/opt/Qt5/lib

Check:

qtchooser -print-env

Reference: man qtchooser

Proper path to qt default config: /usr/lib/x86_64-linux-gnu/qt-default/qtchooser/default.conf