Update Qt 5.9.5 to Qt 5.12 in Ubuntu 18.04 LTS

[Kevin]

A recent article in  Linux Pro Magazine (July 2019 Issue 224) concerned 
the installation of 'Barrier'
allowing use of one mouse/keyboard with two or more computers.
Barrier requires Qt 5.12 as a dependency.

My current setup:
Ubuntu 18 .04 LTS  64 bit (Up to date)
AMD Ryzen 5 2400g
Gnome 3.28.2
Ram 16 GiB

Qt must be installed before 'Barrier'.
If  I install Qt 5.12 what happens to the version already installed by 
Ubuntu.
Do I leave Qt 5.9.5 on the computer as is - do I remove it - do I remove 
it before I install Qt 5.12

I have not been able to find sufficient info online to be of any help.


-- 
Kevin

Ubuntu 18.04.1
Registered User