Affiliates Manager plugin comes with a language folder containing translation files in different languages (“/wp-content/plugins/affiliates-manager/languages”). In order to customize a text message all you need to do is edit the translated string associated with it in your language file.
How to do the translation
Step 1: Check this link which explains how you can create a translation file for your language.
Step 2: Create a new translation file for your language if it already doesn’t exist in the “languages” directory. If it does exist, open it using poedit.
If your Site Language is set to English (United States) open the affiliates-manager-es_ES.po file.
Step 3: The .po file may not be always up to date. So make sure to update it from the plugins POT file.
Step 4: Select a Source Text and customize its output in the Translation field. Click Save when you are done.
Step 5: Add/Update the translation files (both .po and .mo files) for your language in the “languages” folder of the plugin.
Please make sure to keep a backup for your customized language files so you can overwrite it when a new update is released for the plugin.