TT is using a total 1099 Div Summary amount that is significantly more than my input. How do I correct this?

are you in Online version or desktop?

...the desktop menu page summary total includes both box 1a and box 11  (not sure whether any of the other boxes are ever included...2a,b,c,d are not)

I am working on desktop.   Also, yes - the total being use is the sum of boxes 1a and box 11. But is it correct to state my total dividends is the sum of the 2 vs just box 1a. Specifically, when doing foreign tax credit, TT is using the sum of the two to calculate % of income due to foreign sources.

Yes, the sum of box 1a and 11 is used to calculate % of foreign income.