With reference to above reply, this is the properties of the Form as a whole not the individual controls. So you need to amend the Form Properties. This should sort it all out for you.
If you look within the Data properties section (where you made your previous changes) there are two more fields (allow deletions) & (allow addtitions) try changing their properties to NO and this should stop the users adding and deleting records.
Change your subform to design view and select the controls (fields) you want to be read only, then within their properties change the 'Data Locked' property to 'Yes'. This should achieve the result you want. Hope this is of some help.