Browser cache is detected. Browser caching for ….

Cache plugin has no such setting and WP as well. Either you have any other plugin installed or you or anybody else has set this configuration in .htaccess. So check your installed plugin and post your .htaccess please.

cache-control: public, max-age=86400
expires: Thu, 21 Apr 2022 20:16:41 GMT

you need to make expires header timeback to 1981 , and cache-control header to no-cache, must-revalidate, max-age=0 as wordpress default value

you have something in your site , probably some kind of optimization plugin or htaccess rule that altered this , you need to undo that and revert it back to worpdress default way

The following description is my .htaccess file settings.

# BEGIN LSCACHE
## LITESPEED WP CACHE PLUGIN - Do not edit the contents of this block! ##
<IfModule LiteSpeed>
RewriteEngine on
CacheLookup on
RewriteRule .* - [E=Cache-Control:no-autoflush]
RewriteRule \.litespeed_conf\.dat - [F,L]

### marker MOBILE start ###
RewriteCond %{HTTP_USER_AGENT} Mobile|Android|Silk/|Kindle|BlackBerry|Opera\ Mini|Opera\ Mobi [NC]
RewriteRule .* - [E=Cache-Control:vary=%{ENV:LSCACHE_VARY_VALUE}+ismobile]
### marker MOBILE end ###

### marker CACHE RESOURCE start ###
RewriteRule wp-content/.*/[^/]*(responsive|css|js|dynamic|loader|fonts)\.php - [E=cache-control:max-age=3600]
### marker CACHE RESOURCE end ###

### marker FAVICON start ###
RewriteRule favicon\.ico$ - [E=cache-control:max-age=86400]
### marker FAVICON end ###

### marker CORS start ###
<FilesMatch "\.(ttf|ttc|otf|eot|woff|woff2|font\.css)$">
<IfModule mod_headers.c>
Header set Access-Control-Allow-Origin "*"
</IfModule>
</FilesMatch>
### marker CORS end ###

### marker WEBP start ###
RewriteCond %{HTTP_ACCEPT} "image/webp" [or]
RewriteCond %{HTTP_USER_AGENT} "Page Speed"
RewriteRule .* - [E=Cache-Control:vary=%{ENV:LSCACHE_VARY_VALUE}+webp]
RewriteCond %{HTTP_USER_AGENT} iPhone.*Version/(\d{2}).*Safari
RewriteCond %1 >13
RewriteRule .* - [E=Cache-Control:vary=%{ENV:LSCACHE_VARY_VALUE}+webp]
### marker WEBP end ###

### marker DROPQS start ###
CacheKeyModify -qs:fbclid
CacheKeyModify -qs:gclid
CacheKeyModify -qs:utm*
CacheKeyModify -qs:_ga
### marker DROPQS end ###

</IfModule>
## LITESPEED WP CACHE PLUGIN - Do not edit the contents of this block! ##
# END LSCACHE
# BEGIN NON_LSCACHE
## LITESPEED WP CACHE PLUGIN - Do not edit the contents of this block! ##
### marker BROWSER CACHE start ###
<IfModule mod_expires.c>
ExpiresActive on
ExpiresByType application/pdf A31557600
ExpiresByType image/x-icon A31557600
ExpiresByType image/vnd.microsoft.icon A31557600
ExpiresByType image/svg+xml A31557600

ExpiresByType image/jpg A31557600
ExpiresByType image/jpeg A31557600
ExpiresByType image/png A31557600
ExpiresByType image/gif A31557600
ExpiresByType image/webp A31557600

ExpiresByType video/ogg A31557600
ExpiresByType audio/ogg A31557600
ExpiresByType video/mp4 A31557600
ExpiresByType video/webm A31557600

ExpiresByType text/css A31557600
ExpiresByType text/javascript A31557600
ExpiresByType application/javascript A31557600
ExpiresByType application/x-javascript A31557600

ExpiresByType application/x-font-ttf A31557600
ExpiresByType application/x-font-woff A31557600
ExpiresByType application/font-woff A31557600
ExpiresByType application/font-woff2 A31557600
ExpiresByType application/vnd.ms-fontobject A31557600
ExpiresByType font/ttf A31557600
ExpiresByType font/otf A31557600
ExpiresByType font/woff A31557600
ExpiresByType font/woff2 A31557600

</IfModule>
### marker BROWSER CACHE end ###

## LITESPEED WP CACHE PLUGIN - Do not edit the contents of this block! ##
# END NON_LSCACHE

# BEGIN WordPress
# 在含有 BEGIN WordPress 及 END WordPress 標記的這兩行間的指示詞內容為動態產生，
# 且應僅有 WordPress 篩選器能進行修改。對這兩行間任何指示詞內容的變更，
# 都會遭到系統覆寫。
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteRule .* - [E=HTTP_AUTHORIZATION:%{HTTP:Authorization}]
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

Could you please tell me where to modify?

Check your installed plugins that optimizes anything. In .htaccess there is no cache-control for doc defined.

may check the server configuration as well