You don't need a physical pass book for immigration, you just need a bank statement and bank letter. Your SCB account is more of a let's call it a "beginners/easy to use"- account,and you can get the bank statement and the bank letter from your branch when it's time for the 1 year extension. KBanks account together with a K Debit Card and the bank app is imo a notch better.
I would NOT do what you said earlier. Use the SCB account for immigration and KBank for daily expenses as long as you got a K Debit Card, (it's a Visa/ATM card). And download KBanks bank app.
Don't forget that you're applying in Indonesia.German is not the preferred language at the Thai embassy. If you had applied in Germany, a bank statement in German would probably have worked.