A memory can become gentler because the person remembering it has become less threatened.

The same memory softens as your position changes. What was frightening at twenty can be merely sad at forty, not because the event altered but because you are no longer standing where it could reach you. Distance and safety do the work that no amount of deliberate reinterpretation manages.

If something still has teeth, it may simply be that not enough has changed yet, and that is not a failure of effort on your part. Notice which old memories have quietly gone gentle, since that is evidence you are further along than you feel. The rest may need time or a change in circumstance rather than more thinking.