ADC/DAC sampling frequency kcu105 and daq2

i was able to run the evaluation board and i have being working on understanding the code and configuration. i was able to run the fmcdaq2 on 1000 MSPS and i was able to see a output signal in iio oscilloscope. but i can not able to run the 600 MSPS. 

   

AT 600 MSPS.

i have few questions can i change the adc bit values ? and what is the maximum (adc-device-clk.channel divider) value ? can i use 40 MSPS adc for example what is the minimum sampling frequency ?

thank you.

ahmed