Microsoft Project - Start date and task date problem and dates for same task are different in task view and calendar view

Hello,

I'm new to Microsoft Project desktop and am having problems with dates and the calendar.

The first problem I had run into was that I couldn't add dates for a task at any time in August 2025. I could add a date during July 2025 or September 2025, but when I clicked for XX August 2025, it would appear to work, but when I checked, it had changed the date to XX August 2024.

I thought the problem might be the project start date. I want to set the start date to 1 August 2024 (ie, prior to today's date, as some tasks from that period for this project are already complete). Again, when I go to Project/Project Information and make the change, it appears to accept the date, but when I check, it has changed to 1 August 2025.

When looking online, I saw you can also set the start date via File/Info/Project Information. At the moment, it shows 1 August 2024, even though at Project/Project Information, the date is showing as 1 August 2025.

I tried changing the start date to today's date, but then I find that the calendar shows my tasks one year from today (ie, a task that has the correct dates for 2024 in task view shows as exactly one year later, in 2025, in calendar view). I've also spotted that the calendar completely jumps a year from 1 July 2024 to 30 June 2025.

Any help appreciated!