Matter Admins can set coin allowances at both a company-wide level (Default Allowance) and an individual level (Custom Allowance).

To properly configure coins for managers/leadership only, in the Rewards Settings, you'll need to set the Default Allowance to 0 and add a Custom Allowance for each manager.

Since the custom allowance overrides the default allowance, only those specified will be able to give away coins.

Here's an article on how to set default and custom coin allowances.