The true statements about the rules of multiplication for signed numbers are:
- The product of two negative integers is positive.
- If two numbers are the same sign, then the product is positive.
- The product of a positive and a negative is negative.
The other statements are false:
- The product of two integers with different signs is negative, not positive.
- If the signs of two integers are different, then the product is negative, not positive.
So, the three correct options based on the rules of multiplication for signed numbers are the first, third, and second statements as noted above.