We see these discrepancies and gaps in memories, e.g., between a rushed affidavit versus a deliberate interrogation, as evidence of human fallibility, of the Rashomon effect, of people's memories failing them. If you study any other event these types of inconsistencies take place. If these eyewitness accounts were scripted out, if it was directed then there wouldn't be these gaps because everyone would be reading from their preassigned narratives. It would be a seamless narrative.
The conspiracy people see these inconsistencies as nefarious, as not being innocent failures of people's memories. So round and round we go. We see "A" and they see "not A".
If only it were that simple! There are many inconsistencies within the record. Some of these can be chalked up to witnesses changing their minds, or FBI agents failing to accurately reflect what they were told. But not all of them.
Some switcheroos, such as Givens', are obvious lies.
As stated, the give-away is not that his story changed, but that Belin, who'd studied Givens' previous statements, failed to point out that it had changed. And, not only that, that Belin continued to claim Givens' testimony as a key, long after Meagher had pointed out its weakness, and the HSCA had dismissed it entirely.