Good question Nitesh. Currently, the order for the topics on the left navigation is based on the time they have beed added to the navigation. However, I see this useful for our customers to be bale to change the order after an item is added to the navigation bar. Don't you ming to add your great suggestion here: https://community.tribe.so/question/5b88379890ecbe6751123d8b3
This way others will benefit from your note and out product team will ad it to our to-do list if applicable.