Hello James,
Thank you for posting this issue on community forum. Excel on iPad works differently than the desktop version, and unfortunately, formatting text within individual parts of a single cell isn't supported on iPad. When you select text inside a cell, Excel treats the entire cell as a unit, so any formatting applies to the whole cell, not just selected words. A workaround would be to use separate cells for differently formatted text or to create a design using merged cells and different font styles. Another option is to format your schedule in Word or PowerPoint, where text styling within a section is more flexible, and then insert it into Excel as an image if needed. If you're working on a desktop version of Excel, formatting individual parts of text within a cell is possible using the format toolbar.
There's no way to manually unlock this on an iPad, as it's just a limitation of the mobile version.
If you want to know more about Excel formatting refer to this link: Excel formatting basics. Hope this helps. Sincerely,Walter White | Microsoft Community Moderator