I installed the latest version of Qt creator. The scaling works with settings either 100% or 200% in the system. If the system is set in between - 125% for example the Qt creator is not scaled at all and remains in 100%. If the scaling in the system is changed to 200% the size of the creator double. It worked in previous versions.

I haven't changed anything else than updated the creator. The installation was made by the on-line installer.