"How do I pay my promotional accounts before the interest kicks in...?"
Pay the entire amount due by the Due Date. As I understand it, all promos purchases (deferred interest) are "6 months, no interest, if paid in full.." So, pay the entire purchase by the due date (end of 6 months) and you will not pay interest on the purchase. The Due Date for each promo purchase is listed in your account and on your monthly statements.
"... and can I pay a different amount on each one?"
I'm not entirely sure what you mean by this. But, let me answer this way: You are required to make a minimum payment, each month. If you have a promo purchase(s) due within two billing periods, that payment is applied to the promos. (No changing it. And, if the rule applies to promos due more than two months out, I don't know. Ask someone else.) Any payments you make in excess of the minimum are applied to the promos in the order the purchases were made. You can pay any amount you want, and as often as you want (but you must pay the Minimum Due, each month, to remain in good standing and not incur fees).
If you mean can you ay $40 towards a promo due in June and $20 to a promo due in July, etc. Like I said, my experience has been my payments are applied to the closest ones due first. So, that $60 would all go to the promos due in June, if that's the closest-due. If you want PP to break up a payment, or apply a payment to other than the closest due, you would have to call them -- and I'm not sure they would do it. Ask, I totally don't know. BUT, I don't know why it would matter. Pay off the promos that are due the soonest -- get those paid off to avoid interest. Then, make all the payments you can to pay off later-due promos.
(Standard purchases -- those purchases that are not promos -- factor in to the equation... but I'm not going to get into that here.)
That's all I know. 😕
