That's a relief, I thought I was going senile in my old age...
I am not sure that trying to argue about what previous presidents have and haven't done is worth doing. The reasons Americans don't have any meaningful gun control go far beyond what presidents think about it. Obama clearly was desperate to try and get something -- anything -- through, but was unable to pass legislation because Congress was opposed and so was restricted to minor Executive Orders on the subject (several of which have since been rescinded by Trump).
It's therefore hardly Trump's fault personally that Gun Control is not happening right now. On the other hand, what he thinks about it does matter because he leads the party in control of both Houses of Congress and, if he wished, could try to use this position of strength as a platform for pushing some form of gun control legislation through. Of course even then he might still fail -- most House Republicans would block it -- but that he doesn't even try (and, as noted, has if anything taken gun controls backwards in the last year) is still significant.
In the end the US system (and the 2nd Amendment) is what stands in the way. It would probably take a president who commanded a supermajority in both Houses of Congress, as well as one who'd had the time needed to stack the Supreme Court with Liberal judges, *and* a president whose party was also in control of the two-thirds of the state legislatures, in order to turn things around meaningfully. Such a dramatic, and frankly undemocratic, control for one party simply isn't going to happen -- certainly not for gun control advocates, at any rate.