Hi
If you imported your clips directly from your phone to your laptop, they will be somewhere on your laptop, probably your download folder, from where you would load (Add) them to VP. If you save your project and then reopen your vpj project file you will not need to resolve missing files as they will be where you downloaded them to.
If you had VP open and then plugged in your phone, VP will ask if you want to import any files it finds there, in which case they will be saved to the default folder in Options/Disk as Borate mentions and resolution will not be required.
If you loaded the clips into VP from your phone then you can edit etc and save the project as usual but if you then unplug the phone you are removing the storage location, so on opening you project later VP won't find them and will prompt for resolution. Plugging the phone back in will allow VP to find them again.
Always best to keep clips, VP and project file on the same device.
Nat