Craft Edge

I will go through and weld a word together, then go and weld another, both on the same mat, go back to the first and it has come unwelded! What is going on??

I tried to recreate your problem, but when I welded two separate words, they were both welded when I previewed them.

After you weld, click on the magnifying glass icon and view your letters. The red lines that display are the cut lines - anything red will cut. Maybe you don't have the letters overlapping enough. Also, make sure that the Weld checkbox is checked (on the properties window) for each word you want welded. HTH