Qt Creator architecture has nothing to do with the architecture of your application.
To build a 32bit version of your application, use the 32bit package for MSVC2017. The same goes for the 64bit version.
Yeah, that worked. When I tried it in 5.12.0 and failed, there must have been something misconfigured.
I currently don't know for the static version, however when building the dynamic version you can say to configure that it should build dynamic backend selection.
Following some info from another post, I tried the following configure.bat options:-prefix "C:\Qt\Qt5.12.2\5.12.2\msvc2017sr" -release -platform win32-msvc -confirm-license -opensource -nomake examples -nomake tests -static -static-runtime -opengl dynamic -angle -combined-angle-lib -no-feature-d3d12
Now it works on the 32-bit Windows machine I used to build Qt and the application (and still works fine on the 64-bit machine I can also build it on), but when I run it on another Win7 64-bit machine that has never had Qt installed on it, I just get the window frame again. Is it looking for a DLL? I only have a nebulous idea of what some of those configure options actually mean, so I don't know what to try next.