Broken Financial Year

Dear Sir/Madam, I started my business on 01/07/2023. This means that I have a split financial year and my closing date is therefore always 30/06/.. How can I use Dexxter to indicate that my financial year is not the same as the calendar year? Will my personal income tax calculation also be based on my financial year from 01/07/xx to 30/06/xx?
I just wanted to enter my social security contributions from Q1 (01/07/24-30/09/24) and Q2 and Q3. But I get an error message saying that the year 2024 has already been closed. In other words, Dexxter does not know that my financial year 2025 runs from 01/7/24 to 30/06/25.
What should I do?