You must create a brand new shortcut for your AF .exe.
Drop it where ever you want and open up its properties. You will see a Target line. Go to the VERY end of the field past the 'end quotation' mark.
Hit spacebar one time and type in -hires
note: This gives you access to ALL of the resolutions at 32bit. Some people have this option by default, but others do not. So that CMD parameter is optional

Next, hit spacebar one time again, and type in -g5
Hit apply and hit OK.
Launch AF and go to Setup>>Graphics. You should now be able to increase your 'texture detail' & 'object detail' sliders to a higher value.
note: max settings with the -g switch is very taxing on most rigs. You will have to go through a fine tuning process to find the right balance. Futhermore, you won't need to increase your 'object detail' level past 11 (Eleven), its not very noticeable past that value.

Hope this helps.