This question will be better asked in Superuser than when the stack overflows, since this is not about programming, but simply about how to use the command line tool with the correct parameters for the task.
7-Zip comes with a 7-zip.chm help file that can be opened by double-clicking. On the Help tab, Contents, there is an item on the Command Line Version list. First help page for reading 7-Zip from the command line Command line syntax is displayed at the top
7z <command> [<switch> ...] <base_archive_name> [& L; arguments> ...]
Thus, it should be clear from this line that all keys must be specified between the command character and the archive file name. Switches are also supported later on the command line, but nevertheless, you should avoid specifying the keys to the right of the archive file name.
The help page -m (Set compression method) is really not very clear. There are a few examples at the bottom of this man page, but the syntax is not very clear nonetheless.
I think the command line to use with the desired options:
"7z.exe" a -t7z -m0=LZMA2:d64k:fb32 -ms=8m -mmt=30 -mx=1 -- "F:\BACKUP" "D:\Source"
a is the Add command.
-t7z sets the archive type to 7-Zip.
-m0=LZMA2:d64k:fb32 defines the use of the LZMA2 compression method with a dictionary value of 64 KB and a word size (fast bytes) of 32.
-ms=8m allows you to use solid mode with a solid block size of 8 MB.
-mmt=30 allows you to use multithreaded mode with 30 threads.
-mx=1 selects the fastest compression as the compression level.
-- Stops parsing the rest of the keys in the rest of the command line.