I am studying in USA. My family lives in Middle East (not a permanent home country, my father is doing business over there). I born in Middle East and spend most of my life over there. If I go to visit my family in Middle East for 1-2 months, do I have to pray in full or I can shorten the prayers and for how many days? If I go back to my home country for some time, can I shorten the prayers? When I will come back to USA to continue my studies can I shorten my prayers for few days?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.

Whoever travels for a distance of 83 km or more, and his travel is for a permissible purpose, is entitled to shorten the prayers. When he arrives to his home country or to a place where he has a wife, or to a place where he intends to reside for four days or more, then he is not permitted to shorten the prayers. Therefore, it is not permissible for you to shorten the prayers when you return to your home country, or when you travel for studying in another country as most likely you will reside there for a period exceeding four days.

Finally, it should be noted that there are many disadvantages in residing in a non-Muslim country, and it is not permissible to reside there except for a necessity or a dire need, like for the purpose of treatment, or studying a speciality that is not available in Muslim countries and so forth.  

Allaah Knows best.