SAN FRANCISCO » YouTube has reprogrammed its website to make it easier for viewers to find and watch their favorite channels.

The facelift, unveiled Thursday, is the latest step in YouTube’s attempt to make the Internet’s most popular video site as easy to navigate and as compelling to watch as cable TV. In the process, YouTube owner Google Inc. hopes to make money selling ads.

As part of the redesign, YouTube is replacing its staid white background with a touch of gray.

The changes are part of the biggest renovation that YouTube has undertaken since Google bought the site for $1.76 billion five years ago.

Although Google has been steadily adding more frills to YouTube since that acquisition, the videos on the site often were stitched in a crazy quilt that often required visitors to do a lot of searching to find what they wanted.

Google also has been sprucing up other products in recent months, including its Gmail service and news section.

YouTube’s website has been reorganized to display three main vertical columns instead of scattering clips in horizontal rows.

The left of the page is devoted to a column that can be customized to feature a viewer’s favorite channels and monitor the videos being posted by their friends on social networks, including Facebook — a rival to Google’s own Plus service.

The effort to highlight channels comes a few weeks after YouTube agreed to invest $100 million in original programming from about 100 celebrities, media companies and video entrepreneurs. Most of these channels will debut next year. YouTube hopes additional advertising will enable it to reap a profit from the investment.

The middle of YouTube’s new home page is where videos can be played. The selection will change as viewers click on a different channel included in their lists in the left column. The far right column will recommend other videos, based on what kind of clips that viewers have watched in the past.

Bringing more professionally-produced content and more organization to YouTube has become more important since last year’s introduction of Google TV — an attempt to seamlessly blend conventional television programming with Web surfing. YouTube’s more streamlined look might make the site more attractive to watch on large-screen TVs using Google’s product or other connections to the Internet.

Google TV has struggled so far, partly because major Hollywood networks such as News Corp.’s Fox and The Walt Disney Co.’s ABC have blocked their content from the platform because they think it will undercut their advertising revenue and fees from pay-TV distributors such as Comcast Corp. and DirecTV.