Can't Add Paper Size

[Lloyd0]

I was using the same printer before and I was able to add a custom paper size through Printer Properties because this is the window which would appear. 

 

Recently, I switched my printer to another but it was the same exact model but I can't add a custom paper size because the page that appears when I click Printer Properties is this:

 I can't see the option to add a custom paper size anymore. I've tried troubleshooting, and checking drivers. I've also tried adding and saving a New Form to Printer Server Properties but even though the Forms are saved, they are not appearing in the paper sizes in Microsoft Word, etc. I also tried opening HP Smart App because I saw a solution to open Advanced Settings in said app but the page is not opening. It only says "Can't open printer home and EWS page". I don't know of any other way to fix the said problem. Any solution would be highly appreciated. 

[Repairatrooper]

You likely have a different driver installed than  you were using with the other printer. Make sure you have an actual HP driver and not a Microsoft Class or IPP driver.

What happens when you click the advanced tab at the bottom right of the window you posted?

[Lloyd0]

You can choose the paper size but no option to create a custom size. Even the saved forms are not showing up. I checked the drivers, it just says its "Type 4 - User Mode". No idea if that's an HP driver or for windows