Updating a Steel Defender

I admit, I'm probably being thick here... So I created the Steel Defender for our artificer on an NPC character sheet as recommended - the artificer has now levelled so that their proficiency bonus has increased which means the SD needs upgrading. I cannot work out how to! It gets a skill increase, but I can't see how to increase it. Etc etc Any advice please! Thanks in advance

NPC sheets don't have a proficiency bonus calculator built in. You have to manually adjust its attack bonus and skill bonuses. The attack ones are easy to get in and modify. To modify its skill/save bonuses (or base stats) you hover over the main stat block and then you'll see a phantom Cog on the right side. Click on that to put the main stat block into Edit Mode again so you can adjust anything in it.

I was being blind... thank you!