If you are changing all of the columns to the new table/view you can do this by going to your database menu, set datasource location.
In the upper dialog you find the current information, whatever view/table you are currently attached to that you are changing. In the lower part of the dialog you find the new view/table you want to change to.
Once you have the two selected, you click the update button. This switches the two. HOWEVER throughout your report the old table will still look like it is present because it is actually an alias of the true source not the real source.
To fix this:
Once you have completed the switch, you can rename the alias throughout the report. To do this go to 'Database'/'Database Expert'. Your old table name will be in the right side under selected tables.
Click on it, and press F2. You should be able to rename this to whatever you need it to be. There are special character limitations and things like that, but those are as you would expect.
If you just want to change the source of a single column, you can't really do that. The best way to set up your report to reduce this problem is to put the fields into formulas and THEN if you have to modify or change you can just do it in the single location. I never put a field on the canvas, I always wrap it in a formula first. But I'm probably in the minority on that.
If you want to keep your current data source and get data from a different column in a different table/view you can either bring in the other table and do a join or build a new data source in SQL on the server.
Hopefully that answered your question.
