You cannot replace soldered RAM.

No, you can’t swap a soldered RAM chip. That’s not a user-serviceable part — it’s permanently attached to the motherboard.

If you want 12GB total, swap the SODIMM instead. Original config: 4GB soldered + 4GB removable = 8GB. Replace the removable 4GB stick with an 8GB one, and you get 4+8 = 12GB. That works.

The soldered 4GB stays. You can’t make it bigger. The only question is whether the laptop supports mixing different sizes — most do, but check your manual if you want to be sure.

Bottom line: upgrade the slot, not the chip.