Saving changes is not permitted. The changes that you have made require the following tables to be dropped and re-created. You have either made changes to a table that can't be re-created or enabled the option Prevent saving changes that require the table to be re-created.
There is nothing to say, this website below does a great job at explaining how to fix this issue.
The most common operation I usually do is to change a Column Size in Real time.
ALTER TABLE NAMEOFTABLE ALTER COLUMN ycsoftware varchar(1000);
For more information about altering table with Command Lines visit the following Microsoft Article: