update apps

See if you can recover the password to the old ID.

Enter the Apple (iCloud) ID and click Forgot Password.

Apple ID - Manage            

Apple ID – Forgot Password           

One option is to delete the apps/purchases made by the other ID and download them using the new ID if desired. If necessary, check your purchases history to see which apps/purchases weren’t made by the current ID. 

Purchase History Review.   

The first set of instructions work better if done before changing your Apple ID. But, do the best you can with them.

See Change your Apple ID (Be very aware of the restrictions here.) https://support.apple.com/en-us/HT202667

See the section entitled Before changing your Apple ID: It says: "Sign out of all Apple services and devices that use your Apple ID. If you want to use your iPhone, iPad, or iPod touch to change your Apple ID, stay signed in with your Apple ID on only that device."

For sign out purposes, see Where can I use my Apple ID? https://support.apple.com/en-us/HT202659 “This list is provided for informational purposes only and is subject to change without notice. It's not intended to include every feature or service that uses Apple ID. Visit the Apple ID support page for more information.”

There may be some redundancy, but see What to do after you change your Apple ID or password 

 https://support.apple.com/en-us/HT204071

You are welcome. Happy Easter to you.