powerapps pen Input problem

Pen Input control can't hold the signature image. Alternatively, when user submit the form, follow below steps. I know, this is not straight forward, atleast I have not found easy way to achive this.

1. In PowerApps, Send the sign as attachment to selected email id. 

2. In Outlook, Set up  rule to move this to specific folder.

3. Develop a MS Flow to upload this sign image to document library on the same team site.

4. Show the this image on view form using Image control in PowerApps. 

yeah, i am working in Expense Reoprt Form.what is my problem is that first  when i submit the form with signature iam able to see the signature image in my view form.once when i leave the app and login again then the signature is gone. i have attached the screenshots along with this.

image with signature 

once i leave the app