Firstly, in order to modifiy anything, you need to be the admin of your server!
Either by just hosting the server on the same instance you are playing on, or by logging into your server, if you are hosting a dedicated server.

To log into your dedicated server, you will need to have a password set inside the config files.
Once you have everything set up, open your chat, and type #login 'password'.
A message should appear under it stating that you are logged in.

An easy way to check if you are an admin is to just press escape while you are in your server, and look if there is a big debug menu over all your normal options.
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If you wish to change any settings for everyone;

Be in your server and logged in as admin, press escape and go to configure.
There should be a button called "Addon Options".
Click on that. You will find a menu consisting of all the different Ace variables.

At the top we see 3 different charts. Server - Mission - Client

The importent part here is the Server chart! Click on it.
In the drop down menu at the top, go to any specific category you would like to customize.

Adjust your desired setting, and click the right box, where it states "Overwrite Mission".
After clicking the box, a green checkmark should appear next to the setting, verifying that the option applies to your server.

Press OK on the bottom right to apply all changed settings.

Make use of the SAVE button to the left if you wish to make a preset of all the settings you have customized!!
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This should conclude all information that you will need to change Ace values!
If you have any further problems or questions, feel free to ask for help.