Zcash Claymore specifications

I haqve just downloaded Zcash Claymore and in readme file there is something like:

Set the following environment variables, especially if you have 1-2GB cards:

GPU_FORCE_64BIT_PTR 1
GPU_MAX_HEAP_SIZE 100
GPU_USE_SYNC_OBJECTS 1
GPU_MAX_ALLOC_PERCENT 100
GPU_SINGLE_ALLOC_PERCENT 100

Should I set them if I have ASUS rx 480 4gb? Where should I type it?

I cant say for sure but I will tell you that I added the variables in on mine and I run RX-480s and RX-470s.

Where did you typed them in?

On Windows, you should set them in Advanced Settings / Environment Variables. Hit Win+Pause keys to open the dialog box with OS Info. The Advanced Settings link is on the left pane.

You could use this guide:
https://www.techjunkie.com/environment-variables-windows-10/

But where should I typed yhem in if I use Linux?

depends your flavor of Linux. See some help here if you use bash. Best is to make the settings permanent.

you don't with linux