How can I change the folder where LR is saving the tiff files from PS?

Hi, I'm using LR and PS to edit a wedding and imported the RAW files into LR through a USB stick rather than my SD card as I had to move them from another computer. for some reason now the tiff files are being saved back to the USB stick where the original RAW files are. This is causing storage problems as the stick is filling up and I'm having to remove the tiffs and save them on my desktop and then relocate the files each time. How can I change where those tiff are being saved back to?