Question

do you believe that theories can never be proved, only disproved?

Answer 1

In general, that's true. Theories are built up by analyzing many observations. The more observations, the more likely the theory is true. But, one contrary datum will disprove the theory.

Usually, the theory is just modified to account for more details, but occasionally a major upheaval is caused.

Einstein''s theory of relativity did not refute Newton's just extended it to account for relativistic speeds.

Quantum theory is a major departure from classical physics, but on the other hand, it explains observations that cannot be explained by the classical laws of waves/particles. And, really, quantum physics is relatively useless in describing everyday phenomena.