How to set up an active tab in Bitrix?

Question

1C-Bitrix

Good afternoon, I swapped the position of the Tabs (Brought the tab "Characteristics" to the beginning, previously it was "Description") in the template of the detailed product page. Everything works, however, there was a small problem, namely, after all the changes, when you open the product page, the inside of the "Description" section remains active. That is, if you switch to another tab, and then return to the first one, then the necessary "Characteristics" tab will be displayed.
The question is - tell me, please, where does the priority of tabs change?
The body of the tab itself was transferred - it did not remain in the same place where it was originally.
Tab example