I have to use silver shiny embroidering thread, but it keeps on breaking. What can I do to correct this. I use a Brother pe700

This could be a number of things, or a combination of several.

1. Change the needle, as the eye may be burred.
2. Check Upper tension, as it may be incorrect.
3. Check threading. Machines are often threaded incorrectly.
4. Bobbin may also be burred or threaded incorrectly.
5. The upper and lower tension may both be overly tight.
6. Look at the way the thread comes off the spool. It may have a small splinter in the wood or plastic on one end. That would allow you to sew for a bit then the thread would catch and break under the immediate tension increase. Suspect this when the breakage is somewhat regular.
7. Some of the shiny threads are known to have weak points in them. Try a different brand.

My wife and I were sewing professionals and I was a sewing machine mechanic and problem solver. Because of our skills we seldom had difficulties we could not immediately solve. Because of the nature of home sewing machines, they are a bit more fussy than the professional or industrial grades. You will need to use a strong magnifying glass and critical observation to spot burrs in the metal surfaces. However I would consider the bobbin first.

Additionally, I have heard of a special needle designed specifically for metallic threads, but I use specialized industrial machines and have never had the need of one, so my info may be incorrect. You might search online for one and tips for sewing metallic threads.