Is there a way to add a "filter by customer" option on the General Ledger report?

Welcome to the Community, dgonzales.

I can see the relevance of customizing reports to display important information in the appropriate place to review your business finances seamlessly. However, personalizing the General Ledger according to your preferred details is currently unavailable in QuickBooks online.

Therefore, I recommend sending feedback directly to our product development team. Your suggestions can be considered upon working with future product updates to ensure the software meets your business needs.

Here's how:

1. Select the Gear icon, then Feedback.
2. Share your comments or product improvement ideas.
3. Click Next to submit.

You can visit this website to stay updated with your product requests: Customer Feedback for QuickBooks Online.

In the meantime, you can export your reports to Excel and manually edit the data to display Debits, Credits, Bills, Journal Entries, and Balances for each customer separately.

Moreover, you might want to review this material to learn specific methods to customize different financial reports to gather valuable insight about your business: Common custom reports in QuickBooks Online.

Please keep us posted if you have additional questions when generating a report or other related concerns in QuickBooks Online. We are always willing to assist you.

@KimberlyS 

RE: I can see the relevance of customizing reports to display important information in the appropriate place to review your business finances seamlessly.

The OP didn't ask about displaying important information, or putting it in the appropriate place or of reviewing business finances seamlessly, or at all. Or of personalizing the General Ledger, whatever that means.

You could just answer the question. Did you think of that?

@dgonzales-redman  RE: Is there a way to add a "filter by customer" option on the General Ledger report?

No, there isn't. 

The filters are very lame in QuickBooks Online.  Of course  you can do this in QuickBooks Desktop, the real version of QuickBooks.