I am using a Safe drive. What is the procedure for changing the FSoE address of the drive?

You can change the address by writing it into the register: 0x4193 - Safety Address.

Then you have to execute a 'Store Subnode' using the register: 0x46DB - Store Subnode.

You'll see in the link that you'll have to enter a password and this should change the drive address, and keep it after a power cycle.