Hi.
32bit colors are _Unsigned _Long type. (4 bytes). Use _RED32, _GREEN32, _BLUE32, _ALPHA32 for read some bytes, or MEM functions. Then if you use mem, then is byte order ARGB.
For saving values to memory use _MEMFILL or _MEMPUT or PSET, LINE.... for reading values use _MEMGET or POINT (or very old GET method)...
You write color values with C++, right? If is so, try shift bytes order to ARGB.
The color background in QB64 would simply be as follows (pseudo code):
SCREEN _NEWIMAGE (1024,768,32)
CLS, _RGBA32 (0, 255, 0, 255)
or the same thing else
CLS, &HFF00FF00 'alpha, red, green, blue hexadecimal