I can tell that you are a Mac user. This doesn't happen in Windows XP systems as the paste action is specified as "paste unformatted text".
Here's the simplest fix:
Open Manage | Database | Fields. Find this text field and double click it to open field options. Now select the auto-enter tab and enter this calculaiton as an auto-entered calculation:
TextFormatRemove ( self )
Then clear the "do not replace existing values..." check box.
At first I thought it hadn't worked, but as soon as I clicked outside the field after pasting, it reformatted to the field definition. YAY.
It's a real shame that FileMaker doesn't offer this as a standard format option instead of having to find out that it's an obscure (to me) calculation. After all, this is a 50:50 thing.
I have also found that if you press "apple Z" (like an undo) immediately after pasting the text, the formating is removed (on Macs). The calculation Phil mentioned is the better option for fields where you will be pasting into often as you are, but for the occasional use the other method works for some. It would be nice if Mac users had the "paste as unformatted text" option too. (already submitted as feature request by me )
On windows, "paste unformatted" is the only option--so windows users sometimes complain about losing the reverse capability.
And if you are wondering how to post a feature request: Feature Suggestion Form
Mark - I tried Cmd-Z immediately after pasting : it undid the paste!! Are you sure you meant that?
Phil - I will post that feature request. And yes, I quite understand about the 'reverse capability', as for me it's a 50:50 thing; sometimes I want the originating format preserved, other times I want it to take the format of the receiving field.
Yes that usually works. Though most of the time I have that issue is pasting from a different application, like Mail or Word (Acrobat is especially frustrating as it does remove formating but also removes spaces and CRs) . I will have to test that out and see if it applies pasting from one field to another in the same file.
I'm experiencing a similar problem, we copy and paste from a Word document in to FileMaker and it keeps the format of the Word document overriding the field format, is the best way to correct this as above?
As Phil says, the calculation he listed works always for me.
The Command / Control "Z" option always works too, but you must hit Command / Control "Z" (undo) IMMEDIATELY after pasting the value in, as in while the curser is still blinking. It removes the application of (the copy source) text formatting, which is the last step in the paste. If it removes the pasted values, then no foreign formatting was applied.
At least this is my experience, Mac or Windows 7.