When you blow a loud signal

Here the word "you" is plural. Yahweh is speaking to Moses, but he is referring to the priests. The priests will blow the trumpets, Moses will not. AT: "When they blow a loud signal" (See: rc://en/ta/man/translate/figs-you and rc://en/ta/man/translate/figs-metonymy)

the second time

"They" refers to the priests and the word "their" refers to the people of Israel.