You have defined your Item as a plain Number type, so you won’t get any of the UoM features like auto conversion.
You should examine the type of the channel you have linked it to, and try to link like-for-like.
If you must use a Number -
For display only, use a transformation in the [state presentation] field.
Number AeonSocket6Num1 "Garage Miner Socket - Current Consumption [JS(divide1000.js):%s kW]" ....
You’ll find example javascripts to put in your transform folder in this forum.
Yes, because they have been “hijacked” from their display-only role to also provide the Item with a default unit, when given.
This affects persistence, and so affects charting. It’s all a bit clumsy in this area.
Bottom line is to pick your type/unit early then don’t fiddle with it, or you will ruin your persistence history.