Picture Story - How can i prompt ONE Person with different Details?

Hello,
i want to make a Picture Story for Students with Designer Image Creator.

Problem: The Designer make diffrent faces if i want another Details for the following Story.

For Example:
Prompt: "Vocational Student with a hammer".

Result: Nice Color photo with a Vocational Student with black hears... and a hammer.

Prompt: "The same Vocational Student with a screwdriver".
Result: Black white Photo with a different Student. Brown hairs, diffrent face...and a screwdriver.

What can i do to solve this problem?