Thank you for your question -- there is no particular form to fill out -- basically the only thing that changed, is that some "unintended loopholes" have been closed. If you are already drawing benefits, there are no additional benefits to be had. If you have not yet filed for benefits, but are at least 62 by April 30, you can still use the loopholes that have been closed.
Loopholes include the "file and suspend" method - by which one spouse files for benefits, immediately suspends their benefit, and then the other spouse draws a spousal benefit -- while both original benefits continue to grow to their max at age 70.
Another method that is closing is where someone files, and then suspends their benefit -- and does not draw. This is a "free" insurance policy, as if something ever were to happen to them, and they needed a sum of money, they could get benefits retroactive to their filing date. You will no longer be able to do this.
The final method that is closed is where you can choose to take the spouse benefit or ex spouse benefit while allowing your own benefit to continue to grow --- you will have to take the benefit that gives you the larges monthly stipend. You can no longer pick and choose.
Please let me know if you need anything additional. If not, please rate positive.