Luke Ting Hello, thank you for posting. Please see our Spine User Guide - Hotkeys entry on how to find your Hotkeys file. Once your Hotkeys file is open, use Ctrl-F (Windows, Linux) or Cmd-F (Mac) to find the "Weights - Bind: " hotkey that is currently unset and set it to a hotkey of your preference.
Misaki Ting Unfortunately, quite a lot of hotkeys were added, especially in v4.0, and many of the weight view-related hotkeys are not available in v3.8. The only way to use the new hotkeys is to update your editor version.