Can we attach the fabric for the bumpers to the plywood/ and or pool noodles by use of Velcro that way it would be easier for the fabric colors to be interchangeable?

The rules for bumpers and their construction is very specific. Velcro will not hold the fabric in place during collisions.
From <R07>
E. The BUMPERS must be covered with a rugged, smooth cloth (1000 dernier Cordura Plus® strongly recommended). The cloth must completely enclose all exposed surfaces of the BUMPER backing (plywood) and cushion (pool noodle) material. It is recommended that lengths of aluminum angle be used to clamp the fabric in place.

Velcro is not permitted to attach the bumper to the robot <R07> - I.

However, I couldn’t find anything on NOT using velcro to attach fabric to plywood. May be good idea to change colors quickly?

Re read Al’s reply above and the rule <R07>.

Al also didn’t mention the part of the rule about approved methods to change color: base color, with a removable cover.

If you had a nice strong velcro, you could use it for cover attachment, for the non-base cover only. I don’t see anything in the rules against using it for that second cover.

My response just covered the original question about securing the covers to the plywood.

The way I saw it, they were asking if they could attach the base cover with velcro, then pull it off and attach a different one. That’s a definite no-no, under all applicable bumper rules and portions thereof. Using velcro for the outer cover is risky, but quite legal if you can attach it securely.