Hello, I am having troubles in distinguishing between facts and opinions in RC questions, here are few examples that confuse me:

[b]According to mutual fund sales experts, a successful year for a stock fund should result not only in increased investor dollars flowing into the fund, but also in increased investor dollars flowing into other mutual stock funds offered by the same company.
However, while last year the Grafton Mutual Company’s “Growth Stock Fund” beat average market returns by a factor of two and recorded substantial new investment, the other stock funds offered by Grafton did not report any increase whatsoever.

Many People believe that Christopher Columbus was the first European to visit North America. This is grossly untrue, There is well-documented evidence that Leif Erickson and the Vikings visited North America centuries earlier, as well as hypotheses that others even preceded Erickson.

the red statement in the 1st paragraphs is "Conclusions/Opinion" ..why ?
isn't according to experts acts like surveys and findings which are considered as facts??

the red statement in the 2nd paragraphs is "Conclusions/Opinion" ..why ?
moreover many people believe, aren't long held beliefs treated like a premise or fact rather than an opinion?

Thanks.