Relevant Products: Exclaimer Cloud - Signatures for G Suite
You have run the Signature Rules Tester, and the result shown is not the signature that you expected to be applied.
The Signature Rules Tester has a Details tab, which shows the sequence in which signature rules are applied, and which rules are matched (or not):
In the example above, you can see that rules and users are checked for each signature, and results for each signature rule are displayed:
From these details, you can work down the list and identify which signature was applied, and why.