Stock, etc price & data inconsistencies

[dualstow]

I used to think it was google sheets that was the problem, because it has been pulling the wrong price for certain stocks.
I see, though, that it has the right price & price changes for TLT, whereas my (OS X) stock dashboard widget has it wrong.

How do I know what's right and what's wrong? I don't really. I just go with the majority, looking at data from Yahoo Finance and other sources.

I know it shouldn't matter and that we shouldn't look so often, but it kind of does matter.