Batch / Find And Edit Lines in TXT file

I want to create a batch while which finds specific lines in a batch file and are able to edit these lines.

Example:

//TXT FILE//

ex1
ex2
ex3
ex4

i want to let the batch file find ‘ex3’ and edit this to ‘ex5’ to let it look like this:

ex1
ex2
ex5
ex4

Batch / Find And Edit Lines in TXT file