How to make niyyah for ghusl janabah , I usually perform it intending to uplift major sexual impurities. Does this remove my past major sexual impurities too? Jazakallah khair.

All perfect praise be to Allah, The Lord of the Worlds, and peace and blessing be upon the Messenger of Allah, his family, and all his Companions.

The intention of Ghusl for Janabah (state of major impurity due to intimate relations, a wet dream, or sexual discharge) means to intend to remove the state of major ritual impurity or to make prayer and similar worshipful acts that require ritual purity permissible, or intend to perform the obligatory Ghusl. Al-Hadath (state of ritual impurity) is not tangible (like Najasah, i.e., filth), but is rather a state of ritual impurity that affects the body and prevents a person from performing prayer and other worshipful acts that require ritual purity.

If you intend to remove or lift the Hadath, the previous and subsequent ones would be removed as well. For example, if a woman engages in sexual intercourse with her husband at night and she slept before performing Ghusl and they engaged in another intercourse before Fajr Prayer, and she performs Ghusl with the intention of removing the Hadath, the previous and subsequent ones would be removed as well.

If you mean with sexual impurities semen, you should know that semen is ritually pure according to the preponderant scholarly opinion in our view. Assuming that semen is ritually impure, it is adequate to wash off the traces of semen on your body and it is obligatory to hold the intention of removing the ritual impurity because intention is not a condition for the validity of removing the Najasah. If it is removed without holding the intention of removing it, the tainted spot would be purified. If they engage in multiple intercourses before removing the semen and performing Ghusl, there is no problem with that.

Allah knows best.