How do I make niyyah while praying the qadha as I do not remember the days?

Before performing every Qadha, an intention should be made for the Qadha of the specific Salaah missed e.g. when performing Qadha of Zuhr an intention should be made this way that “I am making Qadha of the first Zuhr Qadha that is outstanding upon me as a responsibility.” When this first Zuhr Qadha will be read, then the second one in line will automatically climb up the ladder to the first position. Hence, when performing the next Zuhr Qadha, the same intention will be made (i.e. “I am making Qadha of the first Zuhr Qadha that is outstanding upon me as a responsibility.”). In this way, you will make intention for the other Salaah as well.