How I can alter the automatic reply regarding the number of submissions and the event subscription being closed.

Please would you also tell me how I can alter the automatic reply regarding the number of submissions and the event subscription being closed.

I believe you are referring to the message displayed when a submission limit is reached. Is that correct?

If yes, you can alter the content of the message from the Form settings > Form Status > Warning message as shown below.

I hope this is what you are referring to.

Fantastic. Thank you.
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