I just hate to sew seam, why can’t I just crochet the seams? I have looked several places and its always three needle bind off, mattress stich, etc.:??

There’s no rules that says you can’t, but you may not get the results you want. Crochet is bulkier and usually not invisible. IMO it works best for things like putting squares together for an afghan.

Here’s a good site with still pictures for seams.

Here’s a few crochet seams

The three needle bind off is a way to avoid sewing, it is not sewing. Look in to it a little more; you might like it. It doesn’t work for everything, but it is useful.