Your forum tag indicates you are on Windows, but you’re posting in the Mac tech support section. If you are indeed on a Mac, the method of applying shortcuts is identical to commands that already have shortcuts. You can reference Appendix A.1 in the user manual for instructions.
If you are on Windows then I’m afraid that it is a limitation in how they have things set up, that for the most part only commands with shortcuts can be modified. Hopefully they find a way to improve that in the next version. In the meanwhile the menu accelerator shortcuts, like Alt,f,… are a way of using commands from the keyboard.