Four key Twitter executives are to leave the company as the social network continues its attempt to turn around its fortunes.Twitter`s head of product Kevin Weil and head of media Katie Jacobs Stanton are to leave the company in the coming weeks, as is Alex Roetter, Twitter`s head of engineering. Skip Schipper, who was responsible for human resources matters, is also departing.The news was confirmed in a tweet by chief executive Jack Dorsey on Sunday, who said the foursome could now have some "well-deserved time off".Mr Dorsey - who co-founded Twitter - said when he returned to the company last month that he would make sweeping changes.The first was to lay-off 8% of the company`s workforce - it now seems changes are being made among top executives.Also leaving is Jason Toff, head of Vine, Twitter`s mini-video service. He tweeted that he was to join Google to work on virtual reality.`The world needs Twitter`Writing on blog site Medium, Ms Stanton said her decision was about "time"."While I`ve poured my heart and soul into Twitter," she wrote. "I decided to resign because it`s time for me to pour more of my energy into my family."She later added: "The world needs Twitter and while I will turn in my badge in a few weeks, I will keep rooting (and tweeting!) for Twitter`s continued success."Technology news site Recode reported that the company will soon bring a "well known media personality" to its board of executives, speculating that American Express`s Leslie Berland has been lined up for the role.Twitter`s challenge since hitting the stock market in November 2013 has been to satisfy investors that the 140-character network can sustain growth. To date, it`s largely failed, while newcomers like Snapchat and Instagram have not only captured a younger demographic, but also become sophisticated and lucrative media platforms in their own right.Wooing usersThe site`s attempts to drum up added interest included a high-profile advertisement during American baseball`s World Series.The ad promoted a new feature called Moments, recently rolled out in the UK, which aims to collate news events into a series of key tweets. The goal was to move away from Twitter`s sometimes-overwhelming chronological format.The advert was poorly received, but it is too early to see if Moments has been a success.As head of product, Kevin Weil was responsible for the roll-out of Moments, although he was under the watchful eye of Jack Dorsey who took on a more hands-on development role than his predecessor, Dick Costolo.