report in other then base currency - exchange rate going wild

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hi I use Gnucash on a W7 with american localization. But my accounts
are mainly in CNY and I need reports (profit and loss is something I
am start using now)

what I have noted is that once I put the report currency to CNY the
exchange rate used (for the report) is far off. I my case its 1:10.85
(while it actually is ~1:6.6).
how would you approach this issue ideally? From my perspective the
easiest would be to just define a rate for the report but that does
not seem to exist.

When I look at the price editor I see some strange prices (but can not
actually locate the source of those. Is it save to just delete those
and see how the effect on a report is?