New Ender 3 printing problem - Brittle prints

I just got a Ender 3 as a replacement to my old I3 prusa. When i print the included test print (a dog) it prints really well. however, when i print a .stl that prints fine on my old printer, it prints very brittle. i can cross see sections of the extruded filament when i hold the print to the light.

I think its the Cura settings. The original software that came with the printer is Cura 3.4 and the settings were included but i am using the newest version of Cura, 3.5 which have the ender 3 settings preloaded.

I have done research and it seems like the likely answer is increase flow rate. I was wondering if there is any other recommendation.

Well, i just ended up using the supplied software and settings. it works fine. I have to try to fiure out how to transfer those settings to the newer version.

why not just use the older version of cura ?