In the Design View of the Access Table that you are importing the Excel information to, change the Access Table field type to MEMO for the corresponding EXCEL Field that you wish to import. You do not make any changes in DATASHEET view of either the Access table or the Linked Excel File. It seems like you were trying to make changes to the LINKED XL file instead of importing the XL File content into the structured table in Access.
For example you have 3 Excel Headers
StuffID StuffName StuffDescription
StuffID is a simple serial number
StuffName is a Name less than 255 characters
StuffDescription is a text description which may have more thatn 255 characters depending on the item and depending on the person who is verbosely entering details of the characteristics of said item such that it resembles the chapters of a book on the rise and fall of the third version of said item ad nauseum... you see what I mean.
In Access your Table design would be something like this:
StuffID TYPE= Text (primary Key)
StuffName TYPE = Text
StuffDescription TYPE = MEMO
When the Excel file is imported make sure the wizard knows which fields are being imported to which Access Fields
You shouldn't get any conflicts, but nothing is 100% guaranteed
Goh