As reported on the Quicken community forum when Quicken 2016 R7 US edition (only this release) a QFX file with USD currency is imported on non-USD account (Quicken allows to choose non-USD account during QFX import), the account currency is changed to USD currency. User cannot change the account currency back, so this is considered an issue that hopefully will be changed in next release.
Quicken users face the issue with importing QFX files on non-USD accounts (again, this is about the US edition of Quicken 2016 R7) that could be resolved by changing the currency of the QFX file from non-USD to USD and import the QFX file successfully. With Release 7, importing QFX files with USD currency on non-USD accounts makes the account currency USD.
It is strongly advised to make backup before importing any file into Quicken.
With release R7, Quicken 2016 US edition users have only one option to import transactions into non-USD account: convert to QIF file, import into a proxy CASH account and then move transactions under non-USD account.
The following converters should help with the conversion to QIF format:
FixMyQIF (make various QIF files to follow expected QIF variant)