Let me comment this and other people may check too and see if it is a bug on Quest.

I unchecked the box commanding the game to automatically generate a list of verbs for the objects. However, it still doing so, both on places and objects pane as the inventory as well. As long as i could understand, once this box is unchecked, the verbs should vanish from the player's view. However they still over there. I tried closing the project and loading again, but the problem still there.

just make sure of one thing:

that you don't have for a (or many) specific/individual Object(s) being toggled (under its 'Objects' Tab) to automatically generate a list of verbs for the object, as this may be over-riding the global setting in the 'game' Game object's 'Feature' Tab for that(those) specific/individual Object(s)

I think it generates them based on the verbs you give the object. It still gives them the usual default verbs, but you can change them on the Display Verbs part of the Object tab.

Ahhhh! Ok. It makes some sense now. It only applies to custom verbs, not any pre set verb. Thanks.