Over the years the detail entries in my checking account vary from "T-Mobile/Online PMT" to "T-Mobile payment". Is it possible to do a global search and replace, perhaps in the files with a hex editor (?), to make them all the same?
A similar problem exists with the Interest entry for stock dividends. Some are "Dividend" while others are "_DivInc" or "Dividend Income". Without going one by one and editing, is there a global way to do this? thanks, A

This depends on exactly what field you are trying to change.
If you are trying to "merge" multiple categories, then in the Category View, you can delete a category, and when you do, you can specify a new category to use for any transactions which were using the old category.
KMyMoney does not have a search/replace functionality. One possibility is for transactions in a single account, you can find them by using the filter text field above the ledger. You can then select all relevant transactions and edit them. If you enter the new value in the memo field and save, that value will be used as the memo in all the selected transactions. If that works for you, great, but it doesn't always allow you to save such a change, and I have never been certain what about the selected transactions prevents saving.
A final possibility is to actually edit your data file, using a plain text editor, no need for a hex editor. As always, make a backup copy before trying anything like this. If your data file is encrypted, you need to first decrypt it. If your file is saved as a .kmy file, you can rename from file.kmy to file.xml.gz, and gunzip it. The resulting file.xml (or your original data file, if not compressed) is a plain text file. A plain search/replace will work - but be sure you are just replacing values within a memo field.

I think atheist is talking about the payee field. To merge all those payees into one, go to the payees view, select the payees you want to merge (using Ctrl+left mouse button) and press the merge button (or use the context menu to select it). A dialog will popup and there select the payee you want to keep.

OstroffJH and IPWizard, you both offered valuable advice. I have learned something new. Thank you both very much. A