Hi, to adjust the zoom speed, you first need to go to the keybindings menu (bottom of the left side panel). Then click on motion controller at the top, scroll down about 2/3 down the list, and find the "Increment Origin Forward" keybindings. Change the scale value on those keybindings to change the zoom speed.
For the crash issue, which version of HereSphere are you using? Can you click on "User Guide" at the bottom of the left side panel, then about, to see the version number. I think the crash issue should be fixed on v0.11.0. Let me know if it still crashes on the newest version.