Importing and tab transposition octave issue

The goal is to import bass music and convert it to tab.

Problem 1 - The piece imported fine, but it labeled the part as voice when it should be electric bass. How to you change it in MuseScore 4?

Problem 2 - The tab that I added after the import transposed everything up an octave. How to I transpose it down to the proper tab?

Thank you in advance for the help.