I presently have 16Ft floor trusses joists spanning 16ft4in. They have been strengthened with plywood in certain places because they were put in backward. The fix it sheet was supplied by the truss company.
Its been 10 years now and would like to put ceramic tile on top for flooring. I think there is too much flex and bounce in the floor. They are 24in oc with 3/4 in TG plywood. What do I need to do before I put the tile down??

It's impossible to tell without knowing everything there is to know about the trusses, and the only people who would know all that are the manufacturers. The basic ways to reduce "bounce", which is different from "deflection" are to add mass, such as a 5/8-inch gypsum board ceiling below, or to make the structure stiffer, such as by adding additional trusses, probably not practical, or by adding material to the trusses to increase stiffness. The latter can only be determined by the manufacturer, or by a structural engineer after exhaustive calculations, which the manufacturer has already done.