Currently the stat features in AMX come turned off by default. As there are many options to choose from, you will need to decide what stat's you want enabled. Doing this is fairly easy and can be done two different ways. The first method is with the Stats Settings menu. Below is what the first page looks like. You activate this menu from the amxmodmenu, or by using the amx_statscfgmenu command in your console.
Each stat can be toggled ON or OFF by selecting the number in front of what you want enabled. Option 9 will show you additional stat's not shown in the first page of the menu. If you want the changes you make to be permanent, choose option 8 to save the configuration.
Be aware that you can't have "everything" enabled for a couple reasons. For one, there would be so much text popping up on your screen constantly that is would annoy almost anyone. Second, some options like "Stats at the end of the map" and "Top15 at the end of the map" can't both be on at the same time so you can only choose one.
The second method for restricting weapons is via the server console or using rcon. Type the command amx_restrict in your console. You will get this:
Basically, your commands are:
To show a list of what stat's are available, do amx_statscfg list in the console. The variable column contains the name you use to enable. Here is what amx_statscfg list shows us:
amx_statscfg list 11 will show you additional stat's not shown on the first page of the list. Use the same method for the third (21) and forth (31) page, etc. also.
If you wanted to enable say /top15, you would do it like this:
And then amx_restrict list would show you this:
These changes are kept in a file called stats.ini in the addons\amx\config folder. This is a text file and can be opened as such, but it's recommended to use one of the two methods above for making changes to the stat's. If this file is edited while the server is running, unpredictable results will probably occur. This file doesn't exist until changes are saved using amx_statscfgmenu or amx_statscfg.