When filling out various forms in the left-side menu (Sales, Expenses, Employees, Assets, and Funding), it may happen where certain cells in your grid/planning schedule (located at the bottom of the form) will be inaccessible/grayed out.
For example, you may see something similar to this:

Certain cells in your grid can potentially be grayed out, as seen above. This can be due to a few reasons. Cross check which reason applies to your situation below:

Reason 1: The date selected for the beginning of your budget is AFTER the month selected for the last month of your fiscal year.

For example, you have chosen 2021 as the START of your budget and your fiscal year ends on May. Therefore, all months prior to May 2021 (Jan, Feb, March, April, and May), are unavailable because technically these months have already happened, it is after the month selected for the end of your fiscal year. It is no longer considered part of your budget because budgets/financial forecasts/financial projections deal with the FUTURE, not the PAST. As such, the cells related to these months are unavailable.

Reason 2: The date selected as the start of the form you are filling out begins LATER in your budget.

Although this would not necessarily "gray out" your cells in the grid/planning schedule, Budgeto will still automatically fill out the information in your planning for the appropriate months. If you have chosen a start date that begins later in your budget, all months in your planning prior to that date selected will not be filled out because it supports the information you have entered as the start date for your form. See below for examples:

Your budget starts on January 2021 and you entered an employee that will be hired later in the fiscal year,
Your budget starts on January 2021 and you entered an expense that begins on November 2021,
Your budget starts on January 2021 and you entered a capital asset (company vehicle) that you start paying for on November 2021.

Reason 3: You have entered historical data (either manually or by synchronizing with a supported online accounting system), that occurs PRIOR to the months selected for your budget.

If you have chosen January 2020 as the start of your budget, but have chosen May 2020 as the last month selected from your historical data, then all months prior and including May 2020 will be unavailable/grayed out in your grid because these months have already happened. You have historical information/accounting data relating to these months. Therefore, you can not re-write/modify what is in the past if you have the appropriate information relating to these months.
It is no longer considered part of your budget because budgets/financial forecasts/financial projections deals with the FUTURE, not the PAST. As such, the cells related to these months are grayed out.

For example, I am synchronizing with QuickBooks Online (QBO) and I select the date range to be imported as January 2019-May 2020.

In addition to importing this information, I also select May 2020 as the last month used from my historical information (either from the HISTORICAL DASHBOARD, or by selecting it in my Historical Balance Sheet, or Historical Profit and Loss Statement).

When I go into my Sales forms, I see that the months of January 2020-May 2020 are unavailable/grayed out because these months have already happened. They are in my historical data. Therefore, I need to budget for the later half of the 2020 year (June-December).

When I look at my financial reports, the data for the January 2020-May 2020 will already be there due to my importation with QuickBooks Online (QBO).