You cannot control this in the Memory view, as this is independent of the underlying hardware. The memory view sends a request to the underlying GDB/debugger to read a chunk of memory, and it is then up to the GDB how it reads that memory. For performance reasons, of course GDB will use the most efficient way to read it (words).
So if you want to have byte access, you need to use a plugin like the EmbSysReg viewer which can read it close to the hardware.
Erich