When I accept a new quest, QuickQuest always shares it to my groupmates.

Could you close this feature or add an on/off option, please?

That is an option which is turned off by default, you must have turned it on.
Open up the config window to turn it off again.

Thanks，I will check it later.

Could you help me to find the option please？

It's literally the first one.
If that translation is not accurate enough, feel free to suggest an alternative, the english string is:
"Automatically share quests when picked up"

The first option should be “接受任务后自动分享” in Chinese.

It bothered me for a long time.

Thanks a lot!!!