As the title says, I'm looking for a way to stop containers from resetting, so I can use them to store my stuff. I'm making a player house mod, but can't seem to find the option that enables/disables the resetting of containers. Any help would be great!

That's the "Respawns" flag for CONT records. You don't have to worry about that though as none of Fallout 3's containers respawn except for the vendors'.

I would suggest making a new container because there are mods that change the vanilla containers so they either respawn, or are given random loot 'again'.