Reducing the threshold takes effect immediately upon your action. To increase the threshold, you need to complete full payments to build trust with Facebook. In some cases, you may need to successfully pay at a certain threshold before being eligible for an increase. Therefore, after reducing the threshold, you can still increase it, but it's essential to choose an appropriate time. Absolutely avoid reducing the threshold and immediately increasing it afterward, as Facebook may consider this as unusual activity and may result in account suspension. The process of increasing the threshold occurs gradually, at each level, and you should comply with all of Facebook's policies to maximize the success rate.