The changes are being made to manage demand in the system.
The walk-up community sites are located in Burnley, Hyndburn, Pendle and Preston.
From tomorrow, the walk-up community testing stations across Lancashire will operate from 10am to 3pm, Saturday to Wednesday.
Capacity issues in the national testing system have led to people using the community walk-up sites from other areas.
The walk-up community testing sites are specifically for people in areas of intervention, due to higher numbers of cases.
People from other areas can be turned away.
Dr Sakthi Karunanithi, director of public health for Lancashire, said: "We know that people want to get tested, but there are restrictions in the national system, which are making it harder for us to offer the testing we'd like to do.
"Covid affects everyone, so we all need to do what we can to protect our communities and keep things more normal.
"It’s important that you get tested if you’re showing symptoms, so that we can reduce the spread of Covid.
"Even milder cases, where people don’t end up in hospital, can have serious long-term health impacts.
"By getting tested, you'll know if you need to stay at home so that you don't pass it on to people you know.
"If Covid isn't under control, then we could end up facing further measures which restrict what we can do. We all need to follow the guidance and protect each other."
People should get tested if they’re showing symptoms.
To book a test, call 119 or visit: www.nhs.uk/conditions/coronavirus-covid-19/testing-and-tracing/get-a-test-to-check-if-you-have-coronavirus/
Neil Jack, chair of the regional co-ordination group on the Lancashire Resilience Forum, said: "The demand on the community testing sites has increased enormously since schools reopened, due to lack of laboratory capacity in the national system and the restrictions on available appointments at other sites.
"Lancashire has requested additional testing capacity from the Government, to support the needs of our communities."
As part of the students returning to the University of Central Lancashire, an additional testing site will be in place for four days on their Vernon Street Car Park from tomorrow as well as Friday 18th, Thursday 24th and Friday 25th September.
This site is only for people with symptoms, due to national capacity.
People should book online using the government's portal. Appointments are needed at this site. People should not just turn up.
The university is working with the Lancashire Resilience Forum to look at future testing arrangements on campus which could involve extending the testing facilities further for students, staff and the local community.
Similar mobile testing is being held at the other universities in Lancashire, as part of students' return to campus.
Appointments can be booked by the public, but they are primarily to support students and staff. They can be booked through the Government portal.
There are permanent testing sites in operation at Royal Blackburn Hospital and the Walton-le-Dale Park and Ride near Preston, as well as mobile facilities which are visited on a rota basis. Bookings are needed for these sites via the government portal.
Other testing arrangements are in place in Lancashire for care homes, the NHS and other key workers. Information has been provided to schools, colleges and universities as part of re-opening for the new academic year.