did you restarted the odoo service after changing the conf file ? you are sure that you are in the right conf file itself ?

Actually, I run it on docker. I copied original modules into /mnt/extra-addons/ because when I create a model I want it inherits from /mnt/extra-addons/ instead of /usr/lib/python3/dist-packages/odoo/addons which is the location of original modules. The reason I copy it because sometimes I want to modify the base model so I don't want to ruin the original model. But it seems the system forces me to inherit the original model instead because it's the same module name as the one I copied.