How do turn the temp up on a norlake walkin?

no rule of thumb
maybe if you got a different thermostat that has a lower setting than standard
however as upright freezers are very bad freezers compared to chest type freezers the lowest reading will be around the -35 degrees C
Why very bad -- every time you open the door you dump 20 degrees out onto the floor and the temp difference is more pronounced than opening the lid of a chest unit which keeps all of the cold in the unit
remember the colder the setting the more the compressor is working

if the temp is 10f compressor is fine, just need a tune up, call a specialist.

I would start there. If the thermostat has an off setting, turn it there and see if it goes off. If not, try turning it to it's warmest setting while the box is cold to see if it turns off. To test to see if the relay/ contactor is stuck/bad, kill power to the unit (Unplug or turn off breaker). Disconnect one wire to the thermostat. Restore power. If unit runs, bad relay/contactor. If unit does not run, I'd replace the thermostat. Make sure the sensing bulb of the thermostat is in the conditioned space of the box or in the return air (intake) side of the evap so it can sense the box temp.

Normally freezers are kept at zero. Most health departments will not allow the temp to be higher than plus 10. If you want to store ice cream, you need to be at minus 10 degrees to minus 15 degrees.

let me know if I can be of any further help.

You have to defrost the coil by turnning of the unit and to make it faster leave the inside fan/s running.But if it's building up ice and the fan/s inside works ,is most probably that the unit is low in refrigerant(freon) , or the defrost system is not working.

That noise is typical when the compresor is trying to start but it doesn't , it could be the condensing fan motor that doesn't work and the compresor goes off on overload ; a common problem with this compresors is the relay (mounted at the side of the compresor behind a black plastic cover) goes bad , this you can replace is about $20 , and if still the compresor won't start you will need to put another one and this is an expensive job.

As long as the temp. stays around 5+ or 5- of 0 degrees everything should be okay.

I assume there is no manual control for setting temp. so the thermal sensor or control circuit has failed and it is just staying at its maximum.  You will probably get more help from the manufacturer but their website is somewhat disjointed; looking for contact info for your product ends at one point and then shifts to their scientific product line.
The only general contact info I found is here:
Nor-Lake 
You will in any case need to have the correct model number at hand since the subject line doesn't sound like your freezer. 

Depends on the product you want to keep in the freezer. Usually you want to try and stay between 0 and +10 degrees for most items. Ice Cream must be -10 degrees minimum. Any warmer and it won't keep. Hope this helps.

Good Luck

Check the evaporator coil for frost buildup on the back. Check for frost on the suction line, the biggest line returning to the compressor. If frost is evident at these places you have a defrost system problem. These systems have a defrost timer that defrosts the coil at preset times. Check the timer for proper operation by marking the position of the dial and check back to see if it changes. If it does not change position the timer motor is most likely bad. If the dial is not rotating automatically you can manually turn the dial in the direction of the arrow and put it through a defrost cycle.