I compared those two polls because they asked specifically about declaring war on Germany. The other polls you’re referring to ask less direct questions, such as:
Which of these two things do you think is the more important for the United States to try to do–to keep out of war ourselves or to help England win, even at the risk of getting into the war?
This question, which was asked multiple times between May of 1940 and December of 1941, specifically asks if we should help England even if it risks war, which is different than asking a yes or no question about declaring war on Germany. I acknowledge that responses shifted from 61% saying ‘keep out’ and 35% saying ‘help’ in June 1940, to 68% saying ‘help’ and 28% saying 'keep out" by November 1941, but ‘help’ is not necessarily the same thing as ‘declare war and send troops.’ Also, Germany had already invaded Poland, Belgium, Luxembourg, the Netherlands, and France by the time that June 1940 poll was conducted in which 61% of respondents said ‘keep out.’