how to edit memory using CreateFileMappingA in windows

Question

I have existing file, I want to open that file and map using mapping and edit particular field with some value and create new file. But value is not changing original value is retaining.

Open existing file:

File = CreateFileA(PathFile, GENERIC_READ | GENERIC_WRITE, 0,
    NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);

Create file mapping:

FileMap = CreateFileMappingA(File, NULL, PAGE_READWRITE, 0, 0, NULL);

Map View of file:

ViewBase = MapViewOfFile(FileMap, FILE_MAP_ALL_ACCESS, 0, 0, 0);

Chaging value at particular location:

LocalViewBase= (_DUMP_HEADER64*)ViewBase;
LocalViewBase->DumpType = 0; //for example 1 is replaced with 0

New File copying same contents after modifying particual value DumpType:

count = fwrite(ViewBase, 1, sizeofdata, dumpfile);

In dumpfile after above copy orginal value rained new file creation.