Accordion activate

Accordion activate

Hello everybody,

I have an accordion with three panels. In the third panel, I want a button to select the first panel.

I tried those instructions :
  1. $("#accordion").activate(1);
  2. $("#accordion").activate($("#accordion").children[0]);
  3. $("#accordion").activate("Volet2");
Volet2 is the id of the div in the second panel.

In each case the accordion stayed with panel 3 opened.
I could get panel 1 from the browser console with
  1. $("#accordion").change(1);
but because there was a syntax error, that resulted in going to the first panel opened. I should have got the same thing with
  1. $("#accordion").change(2);
This experience leads me to wonder whether the threads I read, dated 2012, are still up-to-date.
Can anybody indicate me something that works with jquery-3.3.1.js, jquery-ui-git.js, Firefox 62.0.3, and Windows 10 64 bits 1803 ? (and if possible with the update that is waiting for enough place on the disk)