Populate text box if a dropdown field changes

[ahohman]

I have a dropdown field (Yes/No).  If the dropdown is changed, regardless of what is selected, I want the user's name to appear in a text field.  I essentially want to show who changed the dropdown field.  That's it.  See attached screenshot.  Can someone please help?  

Thanks in advance.

[v-albai-msft · Accepted solution]

Hi @ahohman ,

You can use a variable to judge if someone change the dropdown. I have done a test in my side, you can refer to my steps:

1. Set OnChange property of your dropdown field to:

Set(var1,1)

2. Set Text property of your text field to:

If(var1=1,User().FullName)

3. Add another action in the OnSelect property of your Submit button, I just have a simple test below, so there is only one action inside my submit button(this action will clear the value of variable when after user submit his information):

Set(var1,Blank())​

Best Regards,

Allen