Upgrade from 2.3.0.2 to latest version incl Journal template

Hello, I would like help upgrading my store from version 2.3.0.2 to the latest version. Also journal template version 2.7.6 to the latest version.
I have a few minor errors with my store after transferring to a new host with php 7.2 version so I'm hoping that upgrading the store to the latest version will help fix these problems.
The major problems I'm having at the moment is with Paypal and 2checkout plugins. I get permission denied when setting up 2checkout API (even though all admin permissions are selected) so I have to revert to the standard 2checkout extension which doesn't return customers to the store, this results in missing orders. The same happens with Paypal extension, customers are getting confused and duplicating their order payments which is not good. I need good working payment extensions.
Please feel free to send me your offer for this job.

Dear @jrunique,

Greetings!

I can help you with your requirements.

Please check my PM.

Hi JR,
I had sent you PM. Please check inbox

Awaiting reply

Regards
Deep

Hi there,

We should be able to help with this, would you be able to drop us an email to get an estimate?
info@antropy.co.uk

Kind regards,
Alex
www.antropy.co.uk

Hi,
I would be interested as this is within my skill set.
You can reach me on andrewjohnson56782@gmail.com
Best Wishes,
Andrew

Hello,
Please check your PM and let me know. I have relevant experience in an Opencart and ready to help you.
Or you can email me at: shivankagrawal@gmail.com to discuss further.

Thanks,
Shivank Agrawal
Skype: mayank.agrawal2008

Hello,

PM sent. Please check.

Kind Regards,
Manish