>>>>>David,
>>>>>
>>>>>Changing a property in one instance of a form won't change the same property in another instance. Take another look :)
>>>>
>>>>It does seem to do this. I have two numeric fields on my form,(which are each properties of the form). In the first form, when I select a customer, I have code that sums the total value, say 5122.30, for that customer to one of the forms properties.
>>>>
>>>>In a second instance of the form, I select a different customer, and the sum total is say 4120.10. Now if I go back to the first instance of the form, it shows 4120.10 in the text box (instead of remaining 5122.30).
>>>>
>>>It sounds to me like the controlsource of the textbox in question is set to a field reference.
>>
>>I checked this, but both controlsources are Thisform.myvalue1 and Thisform.myvalue2 respectively.
>>
>>(I am using VFP 5.0, and am running the forms in the same VFP session.)
>>
>I don't know what the solution is, but I guarantee that forms don't automatically change properties in other forms. If the controlsource is the form property then you must be doing something in your code. Sorry I can't be of more help, but hopefully my response will help you narrow your debugging.

Are you re-initialising the controlsource in an event that is fired on returning to the form (eg gotfocus).