Hello Luz,
I had understand your concern and tried at my level as per below,
Step 1: Firstly cleared out the purpose to tag dimensions (Use for utilize dimension), and as i can see your snaps, you wanted to use Dimension for tracking cost/ value for any transaction with help of "General Journal",
Step:2 I would say figure out total type of transaction/ Costs you wanted to track or need further analysis based on historical transaction.
( This is step is vital , reason is once you defined "Global Dimension" and "Shortcut Dimension" --> setup at "Gen. Ledger Setup" , and started to using it and later required to change , it is possible to not recommended , reason is it may affect historical transaction where it was used)
More ever as a solution please refer below snaps that my answer your concerns,
Option -1 ( Defined and setup Dimension from Chart of account)

Option 2: Table wise Account dimension setup

Might above information will help it out in a another way.
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Regards,
Rakesh Dobariya