Hi George616,
You need to change the table structure of your table. Instead of using Email as primary key add a column Id and set it to primary key.
Then reference the Id in all child table so the there is no need to change the value in the all tables of database.
When email required for fetching use the Join query to get it.
Example
CREATE TABLE SIGNUP(ID INT PRIMARY KEY,Email VARCHAR(50),CreatedBy VARCHAR(50),CreateDate DATE)
INSERT INTO SIGNUP VALUES(1,'bbbb@gmail.com',NULL,'2020-07-01')
INSERT INTO SIGNUP VALUES(2,'aaaa@yahoo.com',NULL,'2020-07-01')
CREATE TABLE Wallet(Id INT,Uid INT,amount INT)
INSERT INTO Wallet VALUES(1,2,0)
Select Email using Join query.
SELECT w.Id,s.Email,w.amount
FROM Wallet w
INNER JOIN SIGNUP s ON s.ID = w.Uid
