Thanks for reaching out. The legacy version of the Expense Reporting module was disabled and replaced with the new version called Financial Reporting. Even though it won't let you directly edit the start date, you can indirectly choose the start date by which report you select from the base report drop down. Whichever report you select as the base report, it will automatically put the start date as the day after the end date of that base report.
So for example, if you want to run a 2021 annual report, you would need to select a base report that ended on 12/31/2020. It will automatically put 01/01/2021 as the start date and then you just need to enter the end date as 12/31/2021. If you don't have a report that ended on 12/31/2020 yet, then you can create one first by creating an inception - 12/31/2020 report. Or if you want to have annual reports going all the way back, then you can start from the beginning and build them in sequence and it would look something like this:
2016 annual report (base report would be earliest issue date)
2017 annual report (base report would be the 2016 report)
2018 annual report (base report would be the 2017 report)
2019 annual report (base report would be the 2018 report)
And so and so forth.
You can do this for whatever time periods you want whether that's yearly, monthly, quarterly, etc.