If I uninstall the program. When I reinstall, will it pick up the wallet on my PC by default?
Will you reinstall the older version?
Depending on your previous version, it may not be able to read the current wallet file.
If you'll reinstall 4.0.x+, there will be no problem; but if you'll reinstall v3.3.8 and below, you will need to restore using your seed phrase because the upgraded wallet file can't be read by those version.