I love this mod, but I selected the cold setting for the interiors, and I would like to change it to the warm setting for indoors. Do I have to uninstall then reinstall to do this, or is there and easier way?

If you have the mod archive that you downloaded, open it up in 7-zip (or WinRAR or whatever zip manager you use), navigate to the Interiors Warm folder, select the .esp file in that folder and extract it to your Skyrim\Data folder. Open up your mod manager, deactivate the Interiors Cold .esp, and activate the Interiors Warm .esp. Place it in your load order with BOSS (or manually, just put it next to the Interiors Cold file). If you're using a merged or bashed patch, you may want to rebuild that. That should fix it.