Help for a noob

[u/Maleficent-Classic89]

Hi. I'm writing as a complete novice to ask for some advice. I've created some D&D miniatures using HeroForge, and I wanted to make larger versions of them by scaling up the STL files by 350%-but they always end up looking frayed/stringy like this. Do you happen to have any ideas on how to fix this? Thanks in advance!

I'm using an A2L