PyQGIS atlas composer export to PNG with specific name

I want to use PyQGIS3 to export some map composer using atlas,In this task I want to export only one feature from atlas layers to PNG image with specific unique name file.

output='/home/username/Desktop/uniquename.png'
settings = QgsLayoutExporter.ImageExportSettings()
QgsLayoutExporter.exportToImage(myAtlas, output, 'png', settings)

and I get only the default name of file :

output_1.png

How can I change this name with my unique name export?

And I add this lines without and still not work :

#myAtlas.setFilenameExpression(output)
#myAtlas.setPageNameExpression('uniquename')
#myAtlas.filePath(output, 'png')