Can not click icon then change textinput text twice

[JACK_LAI_1117]

HI ALL:

    I have a inputext then I set the Default like this 

Code:

If(
!IsBlank(
LookUp(
'Write-OFF Request',
Title = thistimetitle
).'Column-1'
),
soamailsubject,
"TEST Message"
)

    Then I add a "icon" to let user can update this textinput's  text 
Code

Set(soamailsubject, "Demo Unit Write-Off -"& thistimetitle &" SOA Info information")

    After I test this app , I found something wrong ~~~~

    When user click the icon first time , the textinput's text will change , but after user modify then click again , the textinput's text will not change !!!!!

    I do not know what wrong with my code , so I need your help to overcome this problem , thank you very much !!!!

[RandyHayes · Accepted solution]

@JACK_LAI_1117 

Change your Formula on the OnSelect of your Icon to the following:

Set(soamailsubject, "Demo Unit Write-Off -" & thistimetitle & " SOA Info information");
Reset(yourInputTextControlName)

I hope this is helpful for you. 

[JACK_LAI_1117]

@RandyHayes 

It works .....but I do not know " the reason to reset textinput " ????

Could you help my to get this ??

[RandyHayes]

@JACK_LAI_1117 

So the Reset on the control will put it back to its default value.  If a user types anything in the input control, Default, by itself will not change it...you have to reset at that point.