In file preferenceDlg.cpp line 3021-3024
::SendDlgItemMessage(_hSelf, IDC_CHECK_HBOLD, BM_SETCHECK, nppGUI._printSettings._headerFontStyle & (FONTSTYLE_BOLD ? TRUE : FALSE), 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_HITALIC, BM_SETCHECK, nppGUI._printSettings._headerFontStyle & (FONTSTYLE_ITALIC ? TRUE : FALSE), 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_FBOLD, BM_SETCHECK, nppGUI._printSettings._footerFontStyle & (FONTSTYLE_BOLD ? TRUE : FALSE), 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_FITALIC, BM_SETCHECK, nppGUI._printSettings._footerFontStyle & (FONTSTYLE_ITALIC ? TRUE : FALSE), 0);

the code (FONTSTYLE_BOLD ? TRUE : FALSE) and (FONTSTYLE_ITALIC ? TRUE : FALSE) seems get true ,may be want to likes this:
::SendDlgItemMessage(_hSelf, IDC_CHECK_HBOLD, BM_SETCHECK, nppGUI._printSettings._headerFontStyle & FONTSTYLE_BOLD ? TRUE : FALSE, 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_HITALIC, BM_SETCHECK, nppGUI._printSettings._headerFontStyle & FONTSTYLE_ITALIC ? TRUE : FALSE, 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_FBOLD, BM_SETCHECK, nppGUI._printSettings._footerFontStyle & FONTSTYLE_BOLD ? TRUE : FALSE, 0);
::SendDlgItemMessage(_hSelf, IDC_CHECK_FITALIC, BM_SETCHECK, nppGUI._printSettings._footerFontStyle & FONTSTYLE_ITALIC ? TRUE : FALSE, 0);