Nfc tools is shit but the best I’ve found for mobile programming. First off, protect your tag.(With the dangerous things app) Then get Nfc tools pro. You can save profiles there. Also get the app MIFARE++ Ultralight. It lets you read the raw hex code. It also lets you backup and save what is on your tag so you can have profiles there similar to nfc tools pro. Now to address your issue and explain the shittiness of nfc tools, they write over old records, but don’t clear anything so if I make a nfc tag that is super long but then make a new short command, then everything behind it will be left which will lead to problems down the road. So no you’re not being dumb, its just Nfc tools is a weird program. I also recommend getting NXP taginfo as it has some great read tools. If you need anymore help feel free to ask!